1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
5 <book id="gpuDevelopersGuide">
7 <title>Linux GPU Driver Developer's Guide</title>
11 <firstname>Jesse</firstname>
12 <surname>Barnes</surname>
13 <contrib>Initial version</contrib>
15 <orgname>Intel Corporation</orgname>
17 <email>jesse.barnes@intel.com</email>
22 <firstname>Laurent</firstname>
23 <surname>Pinchart</surname>
24 <contrib>Driver internals</contrib>
26 <orgname>Ideas on board SPRL</orgname>
28 <email>laurent.pinchart@ideasonboard.com</email>
33 <firstname>Daniel</firstname>
34 <surname>Vetter</surname>
35 <contrib>Contributions all over the place</contrib>
37 <orgname>Intel Corporation</orgname>
39 <email>daniel.vetter@ffwll.ch</email>
44 <firstname>Lukas</firstname>
45 <surname>Wunner</surname>
46 <contrib>vga_switcheroo documentation</contrib>
49 <email>lukas@wunner.de</email>
56 <year>2008-2009</year>
57 <year>2013-2014</year>
58 <holder>Intel Corporation</holder>
62 <holder>Laurent Pinchart</holder>
66 <holder>Lukas Wunner</holder>
71 The contents of this file may be used under the terms of the GNU
72 General Public License version 2 (the "GPL") as distributed in
73 the kernel source COPYING file.
78 <!-- Put document revisions here, newest first. -->
80 <revnumber>1.0</revnumber>
81 <date>2012-07-13</date>
82 <authorinitials>LP</authorinitials>
83 <revremark>Added extensive documentation about driver internals.
87 <revnumber>1.1</revnumber>
88 <date>2015-10-11</date>
89 <authorinitials>LW</authorinitials>
90 <revremark>Added vga_switcheroo documentation.
99 <title>DRM Core</title>
102 This first part of the GPU Driver Developer's Guide documents core DRM
103 code, helper libraries for writing drivers and generic userspace
104 interfaces exposed by DRM drivers.
108 <chapter id="drmIntroduction">
109 <title>Introduction</title>
111 The Linux DRM layer contains code intended to support the needs
112 of complex graphics devices, usually containing programmable
113 pipelines well suited to 3D graphics acceleration. Graphics
114 drivers in the kernel may make use of DRM functions to make
115 tasks like memory management, interrupt handling and DMA easier,
116 and provide a uniform interface to applications.
119 A note on versions: this guide covers features found in the DRM
120 tree, including the TTM memory manager, output configuration and
121 mode setting, and the new vblank internals, in addition to all
122 the regular features found in current kernels.
125 [Insert diagram of typical DRM stack here]
131 <chapter id="drmInternals">
132 <title>DRM Internals</title>
134 This chapter documents DRM internals relevant to driver authors
135 and developers working to add support for the latest features to
139 First, we go over some typical driver initialization
140 requirements, like setting up command buffers, creating an
141 initial output configuration, and initializing core services.
142 Subsequent sections cover core internals in more detail,
143 providing implementation notes and examples.
146 The DRM layer provides several services to graphics drivers,
147 many of them driven by the application interfaces it provides
148 through libdrm, the library that wraps most of the DRM ioctls.
149 These include vblank event handling, memory
150 management, output management, framebuffer management, command
151 submission & fencing, suspend/resume support, and DMA
155 <!-- Internals: driver init -->
158 <title>Driver Initialization</title>
160 At the core of every DRM driver is a <structname>drm_driver</structname>
161 structure. Drivers typically statically initialize a drm_driver structure,
162 and then pass it to <function>drm_dev_alloc()</function> to allocate a
163 device instance. After the device instance is fully initialized it can be
164 registered (which makes it accessible from userspace) using
165 <function>drm_dev_register()</function>.
168 The <structname>drm_driver</structname> structure contains static
169 information that describes the driver and features it supports, and
170 pointers to methods that the DRM core will call to implement the DRM API.
171 We will first go through the <structname>drm_driver</structname> static
172 information fields, and will then describe individual operations in
173 details as they get used in later sections.
176 <title>Driver Information</title>
178 <title>Driver Features</title>
180 Drivers inform the DRM core about their requirements and supported
181 features by setting appropriate flags in the
182 <structfield>driver_features</structfield> field. Since those flags
183 influence the DRM core behaviour since registration time, most of them
184 must be set to registering the <structname>drm_driver</structname>
187 <synopsis>u32 driver_features;</synopsis>
189 <title>Driver Feature Flags</title>
191 <term>DRIVER_USE_AGP</term>
193 Driver uses AGP interface, the DRM core will manage AGP resources.
197 <term>DRIVER_REQUIRE_AGP</term>
199 Driver needs AGP interface to function. AGP initialization failure
200 will become a fatal error.
204 <term>DRIVER_PCI_DMA</term>
206 Driver is capable of PCI DMA, mapping of PCI DMA buffers to
207 userspace will be enabled. Deprecated.
211 <term>DRIVER_SG</term>
213 Driver can perform scatter/gather DMA, allocation and mapping of
214 scatter/gather buffers will be enabled. Deprecated.
218 <term>DRIVER_HAVE_DMA</term>
220 Driver supports DMA, the userspace DMA API will be supported.
225 <term>DRIVER_HAVE_IRQ</term><term>DRIVER_IRQ_SHARED</term>
227 DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler
228 managed by the DRM Core. The core will support simple IRQ handler
229 installation when the flag is set. The installation process is
230 described in <xref linkend="drm-irq-registration"/>.</para>
231 <para>DRIVER_IRQ_SHARED indicates whether the device & handler
232 support shared IRQs (note that this is required of PCI drivers).
236 <term>DRIVER_GEM</term>
238 Driver use the GEM memory manager.
242 <term>DRIVER_MODESET</term>
244 Driver supports mode setting interfaces (KMS).
248 <term>DRIVER_PRIME</term>
250 Driver implements DRM PRIME buffer sharing.
254 <term>DRIVER_RENDER</term>
256 Driver supports dedicated render nodes.
260 <term>DRIVER_ATOMIC</term>
262 Driver supports atomic properties. In this case the driver
263 must implement appropriate obj->atomic_get_property() vfuncs
264 for any modeset objects with driver specific properties.
270 <title>Major, Minor and Patchlevel</title>
273 int patchlevel;</synopsis>
275 The DRM core identifies driver versions by a major, minor and patch
276 level triplet. The information is printed to the kernel log at
277 initialization time and passed to userspace through the
278 DRM_IOCTL_VERSION ioctl.
281 The major and minor numbers are also used to verify the requested driver
282 API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes
283 between minor versions, applications can call DRM_IOCTL_SET_VERSION to
284 select a specific version of the API. If the requested major isn't equal
285 to the driver major, or the requested minor is larger than the driver
286 minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise
287 the driver's set_version() method will be called with the requested
292 <title>Name, Description and Date</title>
293 <synopsis>char *name;
295 char *date;</synopsis>
297 The driver name is printed to the kernel log at initialization time,
298 used for IRQ registration and passed to userspace through
302 The driver description is a purely informative string passed to
303 userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by
307 The driver date, formatted as YYYYMMDD, is meant to identify the date of
308 the latest modification to the driver. However, as most drivers fail to
309 update it, its value is mostly useless. The DRM core prints it to the
310 kernel log at initialization time and passes it to userspace through the
311 DRM_IOCTL_VERSION ioctl.
316 <title>Device Instance and Driver Handling</title>
317 !Pdrivers/gpu/drm/drm_drv.c driver instance overview
318 !Edrivers/gpu/drm/drm_drv.c
321 <title>Driver Load</title>
322 <sect3 id="drm-irq-registration">
323 <title>IRQ Registration</title>
325 The DRM core tries to facilitate IRQ handler registration and
326 unregistration by providing <function>drm_irq_install</function> and
327 <function>drm_irq_uninstall</function> functions. Those functions only
328 support a single interrupt per device, devices that use more than one
329 IRQs need to be handled manually.
332 <title>Managed IRQ Registration</title>
334 <function>drm_irq_install</function> starts by calling the
335 <methodname>irq_preinstall</methodname> driver operation. The operation
336 is optional and must make sure that the interrupt will not get fired by
337 clearing all pending interrupt flags or disabling the interrupt.
340 The passed-in IRQ will then be requested by a call to
341 <function>request_irq</function>. If the DRIVER_IRQ_SHARED driver
342 feature flag is set, a shared (IRQF_SHARED) IRQ handler will be
346 The IRQ handler function must be provided as the mandatory irq_handler
347 driver operation. It will get passed directly to
348 <function>request_irq</function> and thus has the same prototype as all
349 IRQ handlers. It will get called with a pointer to the DRM device as the
353 Finally the function calls the optional
354 <methodname>irq_postinstall</methodname> driver operation. The operation
355 usually enables interrupts (excluding the vblank interrupt, which is
356 enabled separately), but drivers may choose to enable/disable interrupts
360 <function>drm_irq_uninstall</function> is similarly used to uninstall an
361 IRQ handler. It starts by waking up all processes waiting on a vblank
362 interrupt to make sure they don't hang, and then calls the optional
363 <methodname>irq_uninstall</methodname> driver operation. The operation
364 must disable all hardware interrupts. Finally the function frees the IRQ
365 by calling <function>free_irq</function>.
369 <title>Manual IRQ Registration</title>
371 Drivers that require multiple interrupt handlers can't use the managed
372 IRQ registration functions. In that case IRQs must be registered and
373 unregistered manually (usually with the <function>request_irq</function>
374 and <function>free_irq</function> functions, or their devm_* equivalent).
377 When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ
378 driver feature flag, and must not provide the
379 <methodname>irq_handler</methodname> driver operation. They must set the
380 <structname>drm_device</structname> <structfield>irq_enabled</structfield>
381 field to 1 upon registration of the IRQs, and clear it to 0 after
382 unregistering the IRQs.
387 <title>Memory Manager Initialization</title>
389 Every DRM driver requires a memory manager which must be initialized at
390 load time. DRM currently contains two memory managers, the Translation
391 Table Manager (TTM) and the Graphics Execution Manager (GEM).
392 This document describes the use of the GEM memory manager only. See
393 <xref linkend="drm-memory-management"/> for details.
397 <title>Miscellaneous Device Configuration</title>
399 Another task that may be necessary for PCI devices during configuration
400 is mapping the video BIOS. On many devices, the VBIOS describes device
401 configuration, LCD panel timings (if any), and contains flags indicating
402 device state. Mapping the BIOS can be done using the pci_map_rom() call,
403 a convenience function that takes care of mapping the actual ROM,
404 whether it has been shadowed into memory (typically at address 0xc0000)
405 or exists on the PCI device in the ROM BAR. Note that after the ROM has
406 been mapped and any necessary information has been extracted, it should
407 be unmapped; on many devices, the ROM address decoder is shared with
408 other BARs, so leaving it mapped could cause undesired behaviour like
409 hangs or memory corruption.
410 <!--!Fdrivers/pci/rom.c pci_map_rom-->
415 <title>Bus-specific Device Registration and PCI Support</title>
417 A number of functions are provided to help with device registration.
418 The functions deal with PCI and platform devices respectively and are
419 only provided for historical reasons. These are all deprecated and
420 shouldn't be used in new drivers. Besides that there's a few
421 helpers for pci drivers.
423 !Edrivers/gpu/drm/drm_pci.c
424 !Edrivers/gpu/drm/drm_platform.c
428 <!-- Internals: memory management -->
430 <sect1 id="drm-memory-management">
431 <title>Memory management</title>
433 Modern Linux systems require large amount of graphics memory to store
434 frame buffers, textures, vertices and other graphics-related data. Given
435 the very dynamic nature of many of that data, managing graphics memory
436 efficiently is thus crucial for the graphics stack and plays a central
437 role in the DRM infrastructure.
440 The DRM core includes two memory managers, namely Translation Table Maps
441 (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory
442 manager to be developed and tried to be a one-size-fits-them all
443 solution. It provides a single userspace API to accommodate the need of
444 all hardware, supporting both Unified Memory Architecture (UMA) devices
445 and devices with dedicated video RAM (i.e. most discrete video cards).
446 This resulted in a large, complex piece of code that turned out to be
447 hard to use for driver development.
450 GEM started as an Intel-sponsored project in reaction to TTM's
451 complexity. Its design philosophy is completely different: instead of
452 providing a solution to every graphics memory-related problems, GEM
453 identified common code between drivers and created a support library to
454 share it. GEM has simpler initialization and execution requirements than
455 TTM, but has no video RAM management capabilities and is thus limited to
459 <title>The Translation Table Manager (TTM)</title>
461 TTM design background and information belongs here.
464 <title>TTM initialization</title>
465 <warning><para>This section is outdated.</para></warning>
467 Drivers wishing to support TTM must fill out a drm_bo_driver
468 structure. The structure contains several fields with function
469 pointers for initializing the TTM, allocating and freeing memory,
470 waiting for command completion and fence synchronization, and memory
471 migration. See the radeon_ttm.c file for an example of usage.
474 The ttm_global_reference structure is made up of several fields:
477 struct ttm_global_reference {
478 enum ttm_global_types global_type;
481 int (*init) (struct ttm_global_reference *);
482 void (*release) (struct ttm_global_reference *);
486 There should be one global reference structure for your memory
487 manager as a whole, and there will be others for each object
488 created by the memory manager at runtime. Your global TTM should
489 have a type of TTM_GLOBAL_TTM_MEM. The size field for the global
490 object should be sizeof(struct ttm_mem_global), and the init and
491 release hooks should point at your driver-specific init and
492 release routines, which probably eventually call
493 ttm_mem_global_init and ttm_mem_global_release, respectively.
496 Once your global TTM accounting structure is set up and initialized
497 by calling ttm_global_item_ref() on it,
498 you need to create a buffer object TTM to
499 provide a pool for buffer object allocation by clients and the
500 kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO,
501 and its size should be sizeof(struct ttm_bo_global). Again,
502 driver-specific init and release functions may be provided,
503 likely eventually calling ttm_bo_global_init() and
504 ttm_bo_global_release(), respectively. Also, like the previous
505 object, ttm_global_item_ref() is used to create an initial reference
506 count for the TTM, which will call your initialization function.
511 <title>The Graphics Execution Manager (GEM)</title>
513 The GEM design approach has resulted in a memory manager that doesn't
514 provide full coverage of all (or even all common) use cases in its
515 userspace or kernel API. GEM exposes a set of standard memory-related
516 operations to userspace and a set of helper functions to drivers, and let
517 drivers implement hardware-specific operations with their own private API.
520 The GEM userspace API is described in the
521 <ulink url="http://lwn.net/Articles/283798/"><citetitle>GEM - the Graphics
522 Execution Manager</citetitle></ulink> article on LWN. While slightly
523 outdated, the document provides a good overview of the GEM API principles.
524 Buffer allocation and read and write operations, described as part of the
525 common GEM API, are currently implemented using driver-specific ioctls.
528 GEM is data-agnostic. It manages abstract buffer objects without knowing
529 what individual buffers contain. APIs that require knowledge of buffer
530 contents or purpose, such as buffer allocation or synchronization
531 primitives, are thus outside of the scope of GEM and must be implemented
532 using driver-specific ioctls.
535 On a fundamental level, GEM involves several operations:
537 <listitem>Memory allocation and freeing</listitem>
538 <listitem>Command execution</listitem>
539 <listitem>Aperture management at command execution time</listitem>
541 Buffer object allocation is relatively straightforward and largely
542 provided by Linux's shmem layer, which provides memory to back each
546 Device-specific operations, such as command execution, pinning, buffer
547 read & write, mapping, and domain ownership transfers are left to
548 driver-specific ioctls.
551 <title>GEM Initialization</title>
553 Drivers that use GEM must set the DRIVER_GEM bit in the struct
554 <structname>drm_driver</structname>
555 <structfield>driver_features</structfield> field. The DRM core will
556 then automatically initialize the GEM core before calling the
557 <methodname>load</methodname> operation. Behind the scene, this will
558 create a DRM Memory Manager object which provides an address space
559 pool for object allocation.
562 In a KMS configuration, drivers need to allocate and initialize a
563 command ring buffer following core GEM initialization if required by
564 the hardware. UMA devices usually have what is called a "stolen"
565 memory region, which provides space for the initial framebuffer and
566 large, contiguous memory regions required by the device. This space is
567 typically not managed by GEM, and must be initialized separately into
568 its own DRM MM object.
572 <title>GEM Objects Creation</title>
574 GEM splits creation of GEM objects and allocation of the memory that
575 backs them in two distinct operations.
578 GEM objects are represented by an instance of struct
579 <structname>drm_gem_object</structname>. Drivers usually need to extend
580 GEM objects with private information and thus create a driver-specific
581 GEM object structure type that embeds an instance of struct
582 <structname>drm_gem_object</structname>.
585 To create a GEM object, a driver allocates memory for an instance of its
586 specific GEM object type and initializes the embedded struct
587 <structname>drm_gem_object</structname> with a call to
588 <function>drm_gem_object_init</function>. The function takes a pointer to
589 the DRM device, a pointer to the GEM object and the buffer object size
593 GEM uses shmem to allocate anonymous pageable memory.
594 <function>drm_gem_object_init</function> will create an shmfs file of
595 the requested size and store it into the struct
596 <structname>drm_gem_object</structname> <structfield>filp</structfield>
597 field. The memory is used as either main storage for the object when the
598 graphics hardware uses system memory directly or as a backing store
602 Drivers are responsible for the actual physical pages allocation by
603 calling <function>shmem_read_mapping_page_gfp</function> for each page.
604 Note that they can decide to allocate pages when initializing the GEM
605 object, or to delay allocation until the memory is needed (for instance
606 when a page fault occurs as a result of a userspace memory access or
607 when the driver needs to start a DMA transfer involving the memory).
610 Anonymous pageable memory allocation is not always desired, for instance
611 when the hardware requires physically contiguous system memory as is
612 often the case in embedded devices. Drivers can create GEM objects with
613 no shmfs backing (called private GEM objects) by initializing them with
614 a call to <function>drm_gem_private_object_init</function> instead of
615 <function>drm_gem_object_init</function>. Storage for private GEM
616 objects must be managed by drivers.
619 Drivers that do not need to extend GEM objects with private information
620 can call the <function>drm_gem_object_alloc</function> function to
621 allocate and initialize a struct <structname>drm_gem_object</structname>
622 instance. The GEM core will call the optional driver
623 <methodname>gem_init_object</methodname> operation after initializing
624 the GEM object with <function>drm_gem_object_init</function>.
625 <synopsis>int (*gem_init_object) (struct drm_gem_object *obj);</synopsis>
628 No alloc-and-init function exists for private GEM objects.
632 <title>GEM Objects Lifetime</title>
634 All GEM objects are reference-counted by the GEM core. References can be
635 acquired and release by <function>calling drm_gem_object_reference</function>
636 and <function>drm_gem_object_unreference</function> respectively. The
637 caller must hold the <structname>drm_device</structname>
638 <structfield>struct_mutex</structfield> lock. As a convenience, GEM
639 provides the <function>drm_gem_object_reference_unlocked</function> and
640 <function>drm_gem_object_unreference_unlocked</function> functions that
641 can be called without holding the lock.
644 When the last reference to a GEM object is released the GEM core calls
645 the <structname>drm_driver</structname>
646 <methodname>gem_free_object</methodname> operation. That operation is
647 mandatory for GEM-enabled drivers and must free the GEM object and all
648 associated resources.
651 <synopsis>void (*gem_free_object) (struct drm_gem_object *obj);</synopsis>
652 Drivers are responsible for freeing all GEM object resources, including
653 the resources created by the GEM core. If an mmap offset has been
654 created for the object (in which case
655 <structname>drm_gem_object</structname>::<structfield>map_list</structfield>::<structfield>map</structfield>
656 is not NULL) it must be freed by a call to
657 <function>drm_gem_free_mmap_offset</function>. The shmfs backing store
658 must be released by calling <function>drm_gem_object_release</function>
659 (that function can safely be called if no shmfs backing store has been
664 <title>GEM Objects Naming</title>
666 Communication between userspace and the kernel refers to GEM objects
667 using local handles, global names or, more recently, file descriptors.
668 All of those are 32-bit integer values; the usual Linux kernel limits
669 apply to the file descriptors.
672 GEM handles are local to a DRM file. Applications get a handle to a GEM
673 object through a driver-specific ioctl, and can use that handle to refer
674 to the GEM object in other standard or driver-specific ioctls. Closing a
675 DRM file handle frees all its GEM handles and dereferences the
676 associated GEM objects.
679 To create a handle for a GEM object drivers call
680 <function>drm_gem_handle_create</function>. The function takes a pointer
681 to the DRM file and the GEM object and returns a locally unique handle.
682 When the handle is no longer needed drivers delete it with a call to
683 <function>drm_gem_handle_delete</function>. Finally the GEM object
684 associated with a handle can be retrieved by a call to
685 <function>drm_gem_object_lookup</function>.
688 Handles don't take ownership of GEM objects, they only take a reference
689 to the object that will be dropped when the handle is destroyed. To
690 avoid leaking GEM objects, drivers must make sure they drop the
691 reference(s) they own (such as the initial reference taken at object
692 creation time) as appropriate, without any special consideration for the
693 handle. For example, in the particular case of combined GEM object and
694 handle creation in the implementation of the
695 <methodname>dumb_create</methodname> operation, drivers must drop the
696 initial reference to the GEM object before returning the handle.
699 GEM names are similar in purpose to handles but are not local to DRM
700 files. They can be passed between processes to reference a GEM object
701 globally. Names can't be used directly to refer to objects in the DRM
702 API, applications must convert handles to names and names to handles
703 using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls
704 respectively. The conversion is handled by the DRM core without any
705 driver-specific support.
708 GEM also supports buffer sharing with dma-buf file descriptors through
709 PRIME. GEM-based drivers must use the provided helpers functions to
710 implement the exporting and importing correctly. See <xref linkend="drm-prime-support" />.
711 Since sharing file descriptors is inherently more secure than the
712 easily guessable and global GEM names it is the preferred buffer
713 sharing mechanism. Sharing buffers through GEM names is only supported
714 for legacy userspace. Furthermore PRIME also allows cross-device
715 buffer sharing since it is based on dma-bufs.
718 <sect3 id="drm-gem-objects-mapping">
719 <title>GEM Objects Mapping</title>
721 Because mapping operations are fairly heavyweight GEM favours
722 read/write-like access to buffers, implemented through driver-specific
723 ioctls, over mapping buffers to userspace. However, when random access
724 to the buffer is needed (to perform software rendering for instance),
725 direct access to the object can be more efficient.
728 The mmap system call can't be used directly to map GEM objects, as they
729 don't have their own file handle. Two alternative methods currently
730 co-exist to map GEM objects to userspace. The first method uses a
731 driver-specific ioctl to perform the mapping operation, calling
732 <function>do_mmap</function> under the hood. This is often considered
733 dubious, seems to be discouraged for new GEM-enabled drivers, and will
734 thus not be described here.
737 The second method uses the mmap system call on the DRM file handle.
738 <synopsis>void *mmap(void *addr, size_t length, int prot, int flags, int fd,
739 off_t offset);</synopsis>
740 DRM identifies the GEM object to be mapped by a fake offset passed
741 through the mmap offset argument. Prior to being mapped, a GEM object
742 must thus be associated with a fake offset. To do so, drivers must call
743 <function>drm_gem_create_mmap_offset</function> on the object. The
744 function allocates a fake offset range from a pool and stores the
745 offset divided by PAGE_SIZE in
746 <literal>obj->map_list.hash.key</literal>. Care must be taken not to
747 call <function>drm_gem_create_mmap_offset</function> if a fake offset
748 has already been allocated for the object. This can be tested by
749 <literal>obj->map_list.map</literal> being non-NULL.
752 Once allocated, the fake offset value
753 (<literal>obj->map_list.hash.key << PAGE_SHIFT</literal>)
754 must be passed to the application in a driver-specific way and can then
755 be used as the mmap offset argument.
758 The GEM core provides a helper method <function>drm_gem_mmap</function>
759 to handle object mapping. The method can be set directly as the mmap
760 file operation handler. It will look up the GEM object based on the
761 offset value and set the VMA operations to the
762 <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield>
763 field. Note that <function>drm_gem_mmap</function> doesn't map memory to
764 userspace, but relies on the driver-provided fault handler to map pages
768 To use <function>drm_gem_mmap</function>, drivers must fill the struct
769 <structname>drm_driver</structname> <structfield>gem_vm_ops</structfield>
770 field with a pointer to VM operations.
773 <synopsis>struct vm_operations_struct *gem_vm_ops
775 struct vm_operations_struct {
776 void (*open)(struct vm_area_struct * area);
777 void (*close)(struct vm_area_struct * area);
778 int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
782 The <methodname>open</methodname> and <methodname>close</methodname>
783 operations must update the GEM object reference count. Drivers can use
784 the <function>drm_gem_vm_open</function> and
785 <function>drm_gem_vm_close</function> helper functions directly as open
789 The fault operation handler is responsible for mapping individual pages
790 to userspace when a page fault occurs. Depending on the memory
791 allocation scheme, drivers can allocate pages at fault time, or can
792 decide to allocate memory for the GEM object at the time the object is
796 Drivers that want to map the GEM object upfront instead of handling page
797 faults can implement their own mmap file operation handler.
801 <title>Memory Coherency</title>
803 When mapped to the device or used in a command buffer, backing pages
804 for an object are flushed to memory and marked write combined so as to
805 be coherent with the GPU. Likewise, if the CPU accesses an object
806 after the GPU has finished rendering to the object, then the object
807 must be made coherent with the CPU's view of memory, usually involving
808 GPU cache flushing of various kinds. This core CPU<->GPU
809 coherency management is provided by a device-specific ioctl, which
810 evaluates an object's current domain and performs any necessary
811 flushing or synchronization to put the object into the desired
812 coherency domain (note that the object may be busy, i.e. an active
813 render target; in that case, setting the domain blocks the client and
814 waits for rendering to complete before performing any necessary
815 flushing operations).
819 <title>Command Execution</title>
821 Perhaps the most important GEM function for GPU devices is providing a
822 command execution interface to clients. Client programs construct
823 command buffers containing references to previously allocated memory
824 objects, and then submit them to GEM. At that point, GEM takes care to
825 bind all the objects into the GTT, execute the buffer, and provide
826 necessary synchronization between clients accessing the same buffers.
827 This often involves evicting some objects from the GTT and re-binding
828 others (a fairly expensive operation), and providing relocation
829 support which hides fixed GTT offsets from clients. Clients must take
830 care not to submit command buffers that reference more objects than
831 can fit in the GTT; otherwise, GEM will reject them and no rendering
832 will occur. Similarly, if several objects in the buffer require fence
833 registers to be allocated for correct rendering (e.g. 2D blits on
834 pre-965 chips), care must be taken not to require more fence registers
835 than are available to the client. Such resource management should be
836 abstracted from the client in libdrm.
840 <title>GEM Function Reference</title>
841 !Edrivers/gpu/drm/drm_gem.c
845 <title>VMA Offset Manager</title>
846 !Pdrivers/gpu/drm/drm_vma_manager.c vma offset manager
847 !Edrivers/gpu/drm/drm_vma_manager.c
848 !Iinclude/drm/drm_vma_manager.h
850 <sect2 id="drm-prime-support">
851 <title>PRIME Buffer Sharing</title>
853 PRIME is the cross device buffer sharing framework in drm, originally
854 created for the OPTIMUS range of multi-gpu platforms. To userspace
855 PRIME buffers are dma-buf based file descriptors.
858 <title>Overview and Driver Interface</title>
860 Similar to GEM global names, PRIME file descriptors are
861 also used to share buffer objects across processes. They offer
862 additional security: as file descriptors must be explicitly sent over
863 UNIX domain sockets to be shared between applications, they can't be
864 guessed like the globally unique GEM names.
867 Drivers that support the PRIME
868 API must set the DRIVER_PRIME bit in the struct
869 <structname>drm_driver</structname>
870 <structfield>driver_features</structfield> field, and implement the
871 <methodname>prime_handle_to_fd</methodname> and
872 <methodname>prime_fd_to_handle</methodname> operations.
875 <synopsis>int (*prime_handle_to_fd)(struct drm_device *dev,
876 struct drm_file *file_priv, uint32_t handle,
877 uint32_t flags, int *prime_fd);
878 int (*prime_fd_to_handle)(struct drm_device *dev,
879 struct drm_file *file_priv, int prime_fd,
880 uint32_t *handle);</synopsis>
881 Those two operations convert a handle to a PRIME file descriptor and
882 vice versa. Drivers must use the kernel dma-buf buffer sharing framework
883 to manage the PRIME file descriptors. Similar to the mode setting
884 API PRIME is agnostic to the underlying buffer object manager, as
885 long as handles are 32bit unsigned integers.
888 While non-GEM drivers must implement the operations themselves, GEM
889 drivers must use the <function>drm_gem_prime_handle_to_fd</function>
890 and <function>drm_gem_prime_fd_to_handle</function> helper functions.
891 Those helpers rely on the driver
892 <methodname>gem_prime_export</methodname> and
893 <methodname>gem_prime_import</methodname> operations to create a dma-buf
894 instance from a GEM object (dma-buf exporter role) and to create a GEM
895 object from a dma-buf instance (dma-buf importer role).
898 <synopsis>struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
899 struct drm_gem_object *obj,
901 struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
902 struct dma_buf *dma_buf);</synopsis>
903 These two operations are mandatory for GEM drivers that support
908 <title>PRIME Helper Functions</title>
909 !Pdrivers/gpu/drm/drm_prime.c PRIME Helpers
913 <title>PRIME Function References</title>
914 !Edrivers/gpu/drm/drm_prime.c
917 <title>DRM MM Range Allocator</title>
919 <title>Overview</title>
920 !Pdrivers/gpu/drm/drm_mm.c Overview
923 <title>LRU Scan/Eviction Support</title>
924 !Pdrivers/gpu/drm/drm_mm.c lru scan roaster
928 <title>DRM MM Range Allocator Function References</title>
929 !Edrivers/gpu/drm/drm_mm.c
930 !Iinclude/drm/drm_mm.h
933 <title>CMA Helper Functions Reference</title>
934 !Pdrivers/gpu/drm/drm_gem_cma_helper.c cma helpers
935 !Edrivers/gpu/drm/drm_gem_cma_helper.c
936 !Iinclude/drm/drm_gem_cma_helper.h
940 <!-- Internals: mode setting -->
942 <sect1 id="drm-mode-setting">
943 <title>Mode Setting</title>
945 Drivers must initialize the mode setting core by calling
946 <function>drm_mode_config_init</function> on the DRM device. The function
947 initializes the <structname>drm_device</structname>
948 <structfield>mode_config</structfield> field and never fails. Once done,
949 mode configuration must be setup by initializing the following fields.
953 <synopsis>int min_width, min_height;
954 int max_width, max_height;</synopsis>
956 Minimum and maximum width and height of the frame buffers in pixel
961 <synopsis>struct drm_mode_config_funcs *funcs;</synopsis>
962 <para>Mode setting functions.</para>
966 <title>Display Modes Function Reference</title>
967 !Iinclude/drm/drm_modes.h
968 !Edrivers/gpu/drm/drm_modes.c
971 <title>Atomic Mode Setting Function Reference</title>
972 !Edrivers/gpu/drm/drm_atomic.c
975 <title>Frame Buffer Creation</title>
976 <synopsis>struct drm_framebuffer *(*fb_create)(struct drm_device *dev,
977 struct drm_file *file_priv,
978 struct drm_mode_fb_cmd2 *mode_cmd);</synopsis>
980 Frame buffers are abstract memory objects that provide a source of
981 pixels to scanout to a CRTC. Applications explicitly request the
982 creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and
983 receive an opaque handle that can be passed to the KMS CRTC control,
984 plane configuration and page flip functions.
987 Frame buffers rely on the underneath memory manager for low-level memory
988 operations. When creating a frame buffer applications pass a memory
989 handle (or a list of memory handles for multi-planar formats) through
990 the <parameter>drm_mode_fb_cmd2</parameter> argument. For drivers using
991 GEM as their userspace buffer management interface this would be a GEM
992 handle. Drivers are however free to use their own backing storage object
993 handles, e.g. vmwgfx directly exposes special TTM handles to userspace
994 and so expects TTM handles in the create ioctl and not GEM handles.
997 Drivers must first validate the requested frame buffer parameters passed
998 through the mode_cmd argument. In particular this is where invalid
999 sizes, pixel formats or pitches can be caught.
1002 If the parameters are deemed valid, drivers then create, initialize and
1003 return an instance of struct <structname>drm_framebuffer</structname>.
1004 If desired the instance can be embedded in a larger driver-specific
1005 structure. Drivers must fill its <structfield>width</structfield>,
1006 <structfield>height</structfield>, <structfield>pitches</structfield>,
1007 <structfield>offsets</structfield>, <structfield>depth</structfield>,
1008 <structfield>bits_per_pixel</structfield> and
1009 <structfield>pixel_format</structfield> fields from the values passed
1010 through the <parameter>drm_mode_fb_cmd2</parameter> argument. They
1011 should call the <function>drm_helper_mode_fill_fb_struct</function>
1012 helper function to do so.
1016 The initialization of the new framebuffer instance is finalized with a
1017 call to <function>drm_framebuffer_init</function> which takes a pointer
1018 to DRM frame buffer operations (struct
1019 <structname>drm_framebuffer_funcs</structname>). Note that this function
1020 publishes the framebuffer and so from this point on it can be accessed
1021 concurrently from other threads. Hence it must be the last step in the
1022 driver's framebuffer initialization sequence. Frame buffer operations
1026 <synopsis>int (*create_handle)(struct drm_framebuffer *fb,
1027 struct drm_file *file_priv, unsigned int *handle);</synopsis>
1029 Create a handle to the frame buffer underlying memory object. If
1030 the frame buffer uses a multi-plane format, the handle will
1031 reference the memory object associated with the first plane.
1034 Drivers call <function>drm_gem_handle_create</function> to create
1039 <synopsis>void (*destroy)(struct drm_framebuffer *framebuffer);</synopsis>
1041 Destroy the frame buffer object and frees all associated
1042 resources. Drivers must call
1043 <function>drm_framebuffer_cleanup</function> to free resources
1044 allocated by the DRM core for the frame buffer object, and must
1045 make sure to unreference all memory objects associated with the
1046 frame buffer. Handles created by the
1047 <methodname>create_handle</methodname> operation are released by
1052 <synopsis>int (*dirty)(struct drm_framebuffer *framebuffer,
1053 struct drm_file *file_priv, unsigned flags, unsigned color,
1054 struct drm_clip_rect *clips, unsigned num_clips);</synopsis>
1056 This optional operation notifies the driver that a region of the
1057 frame buffer has changed in response to a DRM_IOCTL_MODE_DIRTYFB
1064 The lifetime of a drm framebuffer is controlled with a reference count,
1065 drivers can grab additional references with
1066 <function>drm_framebuffer_reference</function>and drop them
1067 again with <function>drm_framebuffer_unreference</function>. For
1068 driver-private framebuffers for which the last reference is never
1069 dropped (e.g. for the fbdev framebuffer when the struct
1070 <structname>drm_framebuffer</structname> is embedded into the fbdev
1071 helper struct) drivers can manually clean up a framebuffer at module
1073 <function>drm_framebuffer_unregister_private</function>.
1077 <title>Dumb Buffer Objects</title>
1079 The KMS API doesn't standardize backing storage object creation and
1080 leaves it to driver-specific ioctls. Furthermore actually creating a
1081 buffer object even for GEM-based drivers is done through a
1082 driver-specific ioctl - GEM only has a common userspace interface for
1083 sharing and destroying objects. While not an issue for full-fledged
1084 graphics stacks that include device-specific userspace components (in
1085 libdrm for instance), this limit makes DRM-based early boot graphics
1086 unnecessarily complex.
1089 Dumb objects partly alleviate the problem by providing a standard
1090 API to create dumb buffers suitable for scanout, which can then be used
1091 to create KMS frame buffers.
1094 To support dumb objects drivers must implement the
1095 <methodname>dumb_create</methodname>,
1096 <methodname>dumb_destroy</methodname> and
1097 <methodname>dumb_map_offset</methodname> operations.
1101 <synopsis>int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev,
1102 struct drm_mode_create_dumb *args);</synopsis>
1104 The <methodname>dumb_create</methodname> operation creates a driver
1105 object (GEM or TTM handle) suitable for scanout based on the
1106 width, height and depth from the struct
1107 <structname>drm_mode_create_dumb</structname> argument. It fills the
1108 argument's <structfield>handle</structfield>,
1109 <structfield>pitch</structfield> and <structfield>size</structfield>
1110 fields with a handle for the newly created object and its line
1111 pitch and size in bytes.
1115 <synopsis>int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev,
1116 uint32_t handle);</synopsis>
1118 The <methodname>dumb_destroy</methodname> operation destroys a dumb
1119 object created by <methodname>dumb_create</methodname>.
1123 <synopsis>int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev,
1124 uint32_t handle, uint64_t *offset);</synopsis>
1126 The <methodname>dumb_map_offset</methodname> operation associates an
1127 mmap fake offset with the object given by the handle and returns
1128 it. Drivers must use the
1129 <function>drm_gem_create_mmap_offset</function> function to
1130 associate the fake offset as described in
1131 <xref linkend="drm-gem-objects-mapping"/>.
1136 Note that dumb objects may not be used for gpu acceleration, as has been
1137 attempted on some ARM embedded platforms. Such drivers really must have
1138 a hardware-specific ioctl to allocate suitable buffer objects.
1142 <title>Output Polling</title>
1143 <synopsis>void (*output_poll_changed)(struct drm_device *dev);</synopsis>
1145 This operation notifies the driver that the status of one or more
1146 connectors has changed. Drivers that use the fb helper can just call the
1147 <function>drm_fb_helper_hotplug_event</function> function to handle this
1152 <title>Locking</title>
1154 Beside some lookup structures with their own locking (which is hidden
1155 behind the interface functions) most of the modeset state is protected
1156 by the <code>dev-<mode_config.lock</code> mutex and additionally
1157 per-crtc locks to allow cursor updates, pageflips and similar operations
1158 to occur concurrently with background tasks like output detection.
1159 Operations which cross domains like a full modeset always grab all
1160 locks. Drivers there need to protect resources shared between crtcs with
1161 additional locking. They also need to be careful to always grab the
1162 relevant crtc locks if a modset functions touches crtc state, e.g. for
1163 load detection (which does only grab the <code>mode_config.lock</code>
1164 to allow concurrent screen updates on live crtcs).
1169 <!-- Internals: kms initialization and cleanup -->
1171 <sect1 id="drm-kms-init">
1172 <title>KMS Initialization and Cleanup</title>
1174 A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders
1175 and connectors. KMS drivers must thus create and initialize all those
1176 objects at load time after initializing mode setting.
1179 <title>CRTCs (struct <structname>drm_crtc</structname>)</title>
1181 A CRTC is an abstraction representing a part of the chip that contains a
1182 pointer to a scanout buffer. Therefore, the number of CRTCs available
1183 determines how many independent scanout buffers can be active at any
1184 given time. The CRTC structure contains several fields to support this:
1185 a pointer to some video memory (abstracted as a frame buffer object), a
1186 display mode, and an (x, y) offset into the video memory to support
1187 panning or configurations where one piece of video memory spans multiple
1191 <title>CRTC Initialization</title>
1193 A KMS device must create and register at least one struct
1194 <structname>drm_crtc</structname> instance. The instance is allocated
1195 and zeroed by the driver, possibly as part of a larger structure, and
1196 registered with a call to <function>drm_crtc_init</function> with a
1197 pointer to CRTC functions.
1200 <sect3 id="drm-kms-crtcops">
1201 <title>CRTC Operations</title>
1203 <title>Set Configuration</title>
1204 <synopsis>int (*set_config)(struct drm_mode_set *set);</synopsis>
1206 Apply a new CRTC configuration to the device. The configuration
1207 specifies a CRTC, a frame buffer to scan out from, a (x,y) position in
1208 the frame buffer, a display mode and an array of connectors to drive
1209 with the CRTC if possible.
1212 If the frame buffer specified in the configuration is NULL, the driver
1213 must detach all encoders connected to the CRTC and all connectors
1214 attached to those encoders and disable them.
1217 This operation is called with the mode config lock held.
1220 Note that the drm core has no notion of restoring the mode setting
1221 state after resume, since all resume handling is in the full
1222 responsibility of the driver. The common mode setting helper library
1223 though provides a helper which can be used for this:
1224 <function>drm_helper_resume_force_mode</function>.
1228 <title>Page Flipping</title>
1229 <synopsis>int (*page_flip)(struct drm_crtc *crtc, struct drm_framebuffer *fb,
1230 struct drm_pending_vblank_event *event);</synopsis>
1232 Schedule a page flip to the given frame buffer for the CRTC. This
1233 operation is called with the mode config mutex held.
1236 Page flipping is a synchronization mechanism that replaces the frame
1237 buffer being scanned out by the CRTC with a new frame buffer during
1238 vertical blanking, avoiding tearing. When an application requests a page
1239 flip the DRM core verifies that the new frame buffer is large enough to
1240 be scanned out by the CRTC in the currently configured mode and then
1241 calls the CRTC <methodname>page_flip</methodname> operation with a
1242 pointer to the new frame buffer.
1245 The <methodname>page_flip</methodname> operation schedules a page flip.
1246 Once any pending rendering targeting the new frame buffer has
1247 completed, the CRTC will be reprogrammed to display that frame buffer
1248 after the next vertical refresh. The operation must return immediately
1249 without waiting for rendering or page flip to complete and must block
1250 any new rendering to the frame buffer until the page flip completes.
1253 If a page flip can be successfully scheduled the driver must set the
1254 <code>drm_crtc->fb</code> field to the new framebuffer pointed to
1255 by <code>fb</code>. This is important so that the reference counting
1256 on framebuffers stays balanced.
1259 If a page flip is already pending, the
1260 <methodname>page_flip</methodname> operation must return
1261 -<errorname>EBUSY</errorname>.
1264 To synchronize page flip to vertical blanking the driver will likely
1265 need to enable vertical blanking interrupts. It should call
1266 <function>drm_vblank_get</function> for that purpose, and call
1267 <function>drm_vblank_put</function> after the page flip completes.
1270 If the application has requested to be notified when page flip completes
1271 the <methodname>page_flip</methodname> operation will be called with a
1272 non-NULL <parameter>event</parameter> argument pointing to a
1273 <structname>drm_pending_vblank_event</structname> instance. Upon page
1274 flip completion the driver must call <methodname>drm_send_vblank_event</methodname>
1275 to fill in the event and send to wake up any waiting processes.
1276 This can be performed with
1277 <programlisting><![CDATA[
1278 spin_lock_irqsave(&dev->event_lock, flags);
1280 drm_send_vblank_event(dev, pipe, event);
1281 spin_unlock_irqrestore(&dev->event_lock, flags);
1282 ]]></programlisting>
1285 FIXME: Could drivers that don't need to wait for rendering to complete
1286 just add the event to <literal>dev->vblank_event_list</literal> and
1287 let the DRM core handle everything, as for "normal" vertical blanking
1291 While waiting for the page flip to complete, the
1292 <literal>event->base.link</literal> list head can be used freely by
1293 the driver to store the pending event in a driver-specific list.
1296 If the file handle is closed before the event is signaled, drivers must
1297 take care to destroy the event in their
1298 <methodname>preclose</methodname> operation (and, if needed, call
1299 <function>drm_vblank_put</function>).
1303 <title>Miscellaneous</title>
1306 <synopsis>void (*set_property)(struct drm_crtc *crtc,
1307 struct drm_property *property, uint64_t value);</synopsis>
1309 Set the value of the given CRTC property to
1310 <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
1311 for more information about properties.
1315 <synopsis>void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
1316 uint32_t start, uint32_t size);</synopsis>
1318 Apply a gamma table to the device. The operation is optional.
1322 <synopsis>void (*destroy)(struct drm_crtc *crtc);</synopsis>
1324 Destroy the CRTC when not needed anymore. See
1325 <xref linkend="drm-kms-init"/>.
1333 <title>Planes (struct <structname>drm_plane</structname>)</title>
1335 A plane represents an image source that can be blended with or overlayed
1336 on top of a CRTC during the scanout process. Planes are associated with
1337 a frame buffer to crop a portion of the image memory (source) and
1338 optionally scale it to a destination size. The result is then blended
1339 with or overlayed on top of a CRTC.
1342 The DRM core recognizes three types of planes:
1345 DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary
1346 planes are the planes operated upon by CRTC modesetting and flipping
1347 operations described in <xref linkend="drm-kms-crtcops"/>.
1350 DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor
1351 planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and
1352 DRM_IOCTL_MODE_CURSOR2 ioctls.
1355 DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes.
1356 Some drivers refer to these types of planes as "sprites" internally.
1359 For compatibility with legacy userspace, only overlay planes are made
1360 available to userspace by default. Userspace clients may set the
1361 DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that
1362 they wish to receive a universal plane list containing all plane types.
1365 <title>Plane Initialization</title>
1367 To create a plane, a KMS drivers allocates and
1368 zeroes an instances of struct <structname>drm_plane</structname>
1369 (possibly as part of a larger structure) and registers it with a call
1370 to <function>drm_universal_plane_init</function>. The function takes a bitmask
1371 of the CRTCs that can be associated with the plane, a pointer to the
1372 plane functions, a list of format supported formats, and the type of
1373 plane (primary, cursor, or overlay) being initialized.
1376 Cursor and overlay planes are optional. All drivers should provide
1377 one primary plane per CRTC (although this requirement may change in
1378 the future); drivers that do not wish to provide special handling for
1379 primary planes may make use of the helper functions described in
1380 <xref linkend="drm-kms-planehelpers"/> to create and register a
1381 primary plane with standard capabilities.
1385 <title>Plane Operations</title>
1388 <synopsis>int (*update_plane)(struct drm_plane *plane, struct drm_crtc *crtc,
1389 struct drm_framebuffer *fb, int crtc_x, int crtc_y,
1390 unsigned int crtc_w, unsigned int crtc_h,
1391 uint32_t src_x, uint32_t src_y,
1392 uint32_t src_w, uint32_t src_h);</synopsis>
1394 Enable and configure the plane to use the given CRTC and frame buffer.
1397 The source rectangle in frame buffer memory coordinates is given by
1398 the <parameter>src_x</parameter>, <parameter>src_y</parameter>,
1399 <parameter>src_w</parameter> and <parameter>src_h</parameter>
1400 parameters (as 16.16 fixed point values). Devices that don't support
1401 subpixel plane coordinates can ignore the fractional part.
1404 The destination rectangle in CRTC coordinates is given by the
1405 <parameter>crtc_x</parameter>, <parameter>crtc_y</parameter>,
1406 <parameter>crtc_w</parameter> and <parameter>crtc_h</parameter>
1407 parameters (as integer values). Devices scale the source rectangle to
1408 the destination rectangle. If scaling is not supported, and the source
1409 rectangle size doesn't match the destination rectangle size, the
1410 driver must return a -<errorname>EINVAL</errorname> error.
1414 <synopsis>int (*disable_plane)(struct drm_plane *plane);</synopsis>
1416 Disable the plane. The DRM core calls this method in response to a
1417 DRM_IOCTL_MODE_SETPLANE ioctl call with the frame buffer ID set to 0.
1418 Disabled planes must not be processed by the CRTC.
1422 <synopsis>void (*destroy)(struct drm_plane *plane);</synopsis>
1424 Destroy the plane when not needed anymore. See
1425 <xref linkend="drm-kms-init"/>.
1432 <title>Encoders (struct <structname>drm_encoder</structname>)</title>
1434 An encoder takes pixel data from a CRTC and converts it to a format
1435 suitable for any attached connectors. On some devices, it may be
1436 possible to have a CRTC send data to more than one encoder. In that
1437 case, both encoders would receive data from the same scanout buffer,
1438 resulting in a "cloned" display configuration across the connectors
1439 attached to each encoder.
1442 <title>Encoder Initialization</title>
1444 As for CRTCs, a KMS driver must create, initialize and register at
1445 least one struct <structname>drm_encoder</structname> instance. The
1446 instance is allocated and zeroed by the driver, possibly as part of a
1450 Drivers must initialize the struct <structname>drm_encoder</structname>
1451 <structfield>possible_crtcs</structfield> and
1452 <structfield>possible_clones</structfield> fields before registering the
1453 encoder. Both fields are bitmasks of respectively the CRTCs that the
1454 encoder can be connected to, and sibling encoders candidate for cloning.
1457 After being initialized, the encoder must be registered with a call to
1458 <function>drm_encoder_init</function>. The function takes a pointer to
1459 the encoder functions and an encoder type. Supported types are
1462 DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A
1465 DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort
1468 DRM_MODE_ENCODER_LVDS for display panels
1471 DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component,
1475 DRM_MODE_ENCODER_VIRTUAL for virtual machine displays
1480 Encoders must be attached to a CRTC to be used. DRM drivers leave
1481 encoders unattached at initialization time. Applications (or the fbdev
1482 compatibility layer when implemented) are responsible for attaching the
1483 encoders they want to use to a CRTC.
1487 <title>Encoder Operations</title>
1490 <synopsis>void (*destroy)(struct drm_encoder *encoder);</synopsis>
1492 Called to destroy the encoder when not needed anymore. See
1493 <xref linkend="drm-kms-init"/>.
1497 <synopsis>void (*set_property)(struct drm_plane *plane,
1498 struct drm_property *property, uint64_t value);</synopsis>
1500 Set the value of the given plane property to
1501 <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
1502 for more information about properties.
1509 <title>Connectors (struct <structname>drm_connector</structname>)</title>
1511 A connector is the final destination for pixel data on a device, and
1512 usually connects directly to an external display device like a monitor
1513 or laptop panel. A connector can only be attached to one encoder at a
1514 time. The connector is also the structure where information about the
1515 attached display is kept, so it contains fields for display data, EDID
1516 data, DPMS & connection status, and information about modes
1517 supported on the attached displays.
1520 <title>Connector Initialization</title>
1522 Finally a KMS driver must create, initialize, register and attach at
1523 least one struct <structname>drm_connector</structname> instance. The
1524 instance is created as other KMS objects and initialized by setting the
1529 <term><structfield>interlace_allowed</structfield></term>
1531 Whether the connector can handle interlaced modes.
1535 <term><structfield>doublescan_allowed</structfield></term>
1537 Whether the connector can handle doublescan.
1541 <term><structfield>display_info
1542 </structfield></term>
1544 Display information is filled from EDID information when a display
1545 is detected. For non hot-pluggable displays such as flat panels in
1546 embedded systems, the driver should initialize the
1547 <structfield>display_info</structfield>.<structfield>width_mm</structfield>
1549 <structfield>display_info</structfield>.<structfield>height_mm</structfield>
1550 fields with the physical size of the display.
1554 <term id="drm-kms-connector-polled"><structfield>polled</structfield></term>
1556 Connector polling mode, a combination of
1559 <term>DRM_CONNECTOR_POLL_HPD</term>
1561 The connector generates hotplug events and doesn't need to be
1562 periodically polled. The CONNECT and DISCONNECT flags must not
1563 be set together with the HPD flag.
1567 <term>DRM_CONNECTOR_POLL_CONNECT</term>
1569 Periodically poll the connector for connection.
1573 <term>DRM_CONNECTOR_POLL_DISCONNECT</term>
1575 Periodically poll the connector for disconnection.
1579 Set to 0 for connectors that don't support connection status
1585 The connector is then registered with a call to
1586 <function>drm_connector_init</function> with a pointer to the connector
1587 functions and a connector type, and exposed through sysfs with a call to
1588 <function>drm_connector_register</function>.
1591 Supported connector types are
1593 <listitem>DRM_MODE_CONNECTOR_VGA</listitem>
1594 <listitem>DRM_MODE_CONNECTOR_DVII</listitem>
1595 <listitem>DRM_MODE_CONNECTOR_DVID</listitem>
1596 <listitem>DRM_MODE_CONNECTOR_DVIA</listitem>
1597 <listitem>DRM_MODE_CONNECTOR_Composite</listitem>
1598 <listitem>DRM_MODE_CONNECTOR_SVIDEO</listitem>
1599 <listitem>DRM_MODE_CONNECTOR_LVDS</listitem>
1600 <listitem>DRM_MODE_CONNECTOR_Component</listitem>
1601 <listitem>DRM_MODE_CONNECTOR_9PinDIN</listitem>
1602 <listitem>DRM_MODE_CONNECTOR_DisplayPort</listitem>
1603 <listitem>DRM_MODE_CONNECTOR_HDMIA</listitem>
1604 <listitem>DRM_MODE_CONNECTOR_HDMIB</listitem>
1605 <listitem>DRM_MODE_CONNECTOR_TV</listitem>
1606 <listitem>DRM_MODE_CONNECTOR_eDP</listitem>
1607 <listitem>DRM_MODE_CONNECTOR_VIRTUAL</listitem>
1611 Connectors must be attached to an encoder to be used. For devices that
1612 map connectors to encoders 1:1, the connector should be attached at
1613 initialization time with a call to
1614 <function>drm_mode_connector_attach_encoder</function>. The driver must
1615 also set the <structname>drm_connector</structname>
1616 <structfield>encoder</structfield> field to point to the attached
1620 Finally, drivers must initialize the connectors state change detection
1621 with a call to <function>drm_kms_helper_poll_init</function>. If at
1622 least one connector is pollable but can't generate hotplug interrupts
1623 (indicated by the DRM_CONNECTOR_POLL_CONNECT and
1624 DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will
1625 automatically be queued to periodically poll for changes. Connectors
1626 that can generate hotplug interrupts must be marked with the
1627 DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must
1628 call <function>drm_helper_hpd_irq_event</function>. The function will
1629 queue a delayed work to check the state of all connectors, but no
1630 periodic polling will be done.
1634 <title>Connector Operations</title>
1636 Unless otherwise state, all operations are mandatory.
1640 <synopsis>void (*dpms)(struct drm_connector *connector, int mode);</synopsis>
1642 The DPMS operation sets the power state of a connector. The mode
1645 <listitem><para>DRM_MODE_DPMS_ON</para></listitem>
1646 <listitem><para>DRM_MODE_DPMS_STANDBY</para></listitem>
1647 <listitem><para>DRM_MODE_DPMS_SUSPEND</para></listitem>
1648 <listitem><para>DRM_MODE_DPMS_OFF</para></listitem>
1652 In all but DPMS_ON mode the encoder to which the connector is attached
1653 should put the display in low-power mode by driving its signals
1654 appropriately. If more than one connector is attached to the encoder
1655 care should be taken not to change the power state of other displays as
1656 a side effect. Low-power mode should be propagated to the encoders and
1657 CRTCs when all related connectors are put in low-power mode.
1661 <title>Modes</title>
1662 <synopsis>int (*fill_modes)(struct drm_connector *connector, uint32_t max_width,
1663 uint32_t max_height);</synopsis>
1665 Fill the mode list with all supported modes for the connector. If the
1666 <parameter>max_width</parameter> and <parameter>max_height</parameter>
1667 arguments are non-zero, the implementation must ignore all modes wider
1668 than <parameter>max_width</parameter> or higher than
1669 <parameter>max_height</parameter>.
1672 The connector must also fill in this operation its
1673 <structfield>display_info</structfield>
1674 <structfield>width_mm</structfield> and
1675 <structfield>height_mm</structfield> fields with the connected display
1676 physical size in millimeters. The fields should be set to 0 if the value
1677 isn't known or is not applicable (for instance for projector devices).
1681 <title>Connection Status</title>
1683 The connection status is updated through polling or hotplug events when
1684 supported (see <xref linkend="drm-kms-connector-polled"/>). The status
1685 value is reported to userspace through ioctls and must not be used
1686 inside the driver, as it only gets initialized by a call to
1687 <function>drm_mode_getconnector</function> from userspace.
1689 <synopsis>enum drm_connector_status (*detect)(struct drm_connector *connector,
1690 bool force);</synopsis>
1692 Check to see if anything is attached to the connector. The
1693 <parameter>force</parameter> parameter is set to false whilst polling or
1694 to true when checking the connector due to user request.
1695 <parameter>force</parameter> can be used by the driver to avoid
1696 expensive, destructive operations during automated probing.
1699 Return connector_status_connected if something is connected to the
1700 connector, connector_status_disconnected if nothing is connected and
1701 connector_status_unknown if the connection state isn't known.
1704 Drivers should only return connector_status_connected if the connection
1705 status has really been probed as connected. Connectors that can't detect
1706 the connection status, or failed connection status probes, should return
1707 connector_status_unknown.
1711 <title>Miscellaneous</title>
1714 <synopsis>void (*set_property)(struct drm_connector *connector,
1715 struct drm_property *property, uint64_t value);</synopsis>
1717 Set the value of the given connector property to
1718 <parameter>value</parameter>. See <xref linkend="drm-kms-properties"/>
1719 for more information about properties.
1723 <synopsis>void (*destroy)(struct drm_connector *connector);</synopsis>
1725 Destroy the connector when not needed anymore. See
1726 <xref linkend="drm-kms-init"/>.
1734 <title>Cleanup</title>
1736 The DRM core manages its objects' lifetime. When an object is not needed
1737 anymore the core calls its destroy function, which must clean up and
1738 free every resource allocated for the object. Every
1739 <function>drm_*_init</function> call must be matched with a
1740 corresponding <function>drm_*_cleanup</function> call to cleanup CRTCs
1741 (<function>drm_crtc_cleanup</function>), planes
1742 (<function>drm_plane_cleanup</function>), encoders
1743 (<function>drm_encoder_cleanup</function>) and connectors
1744 (<function>drm_connector_cleanup</function>). Furthermore, connectors
1745 that have been added to sysfs must be removed by a call to
1746 <function>drm_connector_unregister</function> before calling
1747 <function>drm_connector_cleanup</function>.
1750 Connectors state change detection must be cleanup up with a call to
1751 <function>drm_kms_helper_poll_fini</function>.
1755 <title>Output discovery and initialization example</title>
1756 <programlisting><![CDATA[
1757 void intel_crt_init(struct drm_device *dev)
1759 struct drm_connector *connector;
1760 struct intel_output *intel_output;
1762 intel_output = kzalloc(sizeof(struct intel_output), GFP_KERNEL);
1766 connector = &intel_output->base;
1767 drm_connector_init(dev, &intel_output->base,
1768 &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);
1770 drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs,
1771 DRM_MODE_ENCODER_DAC);
1773 drm_mode_connector_attach_encoder(&intel_output->base,
1774 &intel_output->enc);
1776 /* Set up the DDC bus. */
1777 intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A");
1778 if (!intel_output->ddc_bus) {
1779 dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration "
1784 intel_output->type = INTEL_OUTPUT_ANALOG;
1785 connector->interlace_allowed = 0;
1786 connector->doublescan_allowed = 0;
1788 drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs);
1789 drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);
1791 drm_connector_register(connector);
1792 }]]></programlisting>
1794 In the example above (taken from the i915 driver), a CRTC, connector and
1795 encoder combination is created. A device-specific i2c bus is also
1796 created for fetching EDID data and performing monitor detection. Once
1797 the process is complete, the new connector is registered with sysfs to
1798 make its properties available to applications.
1802 <title>KMS API Functions</title>
1803 !Edrivers/gpu/drm/drm_crtc.c
1806 <title>KMS Data Structures</title>
1807 !Iinclude/drm/drm_crtc.h
1810 <title>KMS Locking</title>
1811 !Pdrivers/gpu/drm/drm_modeset_lock.c kms locking
1812 !Iinclude/drm/drm_modeset_lock.h
1813 !Edrivers/gpu/drm/drm_modeset_lock.c
1817 <!-- Internals: kms helper functions -->
1820 <title>Mode Setting Helper Functions</title>
1822 The plane, CRTC, encoder and connector functions provided by the drivers
1823 implement the DRM API. They're called by the DRM core and ioctl handlers
1824 to handle device state changes and configuration request. As implementing
1825 those functions often requires logic not specific to drivers, mid-layer
1826 helper functions are available to avoid duplicating boilerplate code.
1829 The DRM core contains one mid-layer implementation. The mid-layer provides
1830 implementations of several plane, CRTC, encoder and connector functions
1831 (called from the top of the mid-layer) that pre-process requests and call
1832 lower-level functions provided by the driver (at the bottom of the
1833 mid-layer). For instance, the
1834 <function>drm_crtc_helper_set_config</function> function can be used to
1835 fill the struct <structname>drm_crtc_funcs</structname>
1836 <structfield>set_config</structfield> field. When called, it will split
1837 the <methodname>set_config</methodname> operation in smaller, simpler
1838 operations and call the driver to handle them.
1841 To use the mid-layer, drivers call <function>drm_crtc_helper_add</function>,
1842 <function>drm_encoder_helper_add</function> and
1843 <function>drm_connector_helper_add</function> functions to install their
1844 mid-layer bottom operations handlers, and fill the
1845 <structname>drm_crtc_funcs</structname>,
1846 <structname>drm_encoder_funcs</structname> and
1847 <structname>drm_connector_funcs</structname> structures with pointers to
1848 the mid-layer top API functions. Installing the mid-layer bottom operation
1849 handlers is best done right after registering the corresponding KMS object.
1852 The mid-layer is not split between CRTC, encoder and connector operations.
1853 To use it, a driver must provide bottom functions for all of the three KMS
1857 <title>Helper Functions</title>
1860 <synopsis>int drm_crtc_helper_set_config(struct drm_mode_set *set);</synopsis>
1862 The <function>drm_crtc_helper_set_config</function> helper function
1863 is a CRTC <methodname>set_config</methodname> implementation. It
1864 first tries to locate the best encoder for each connector by calling
1865 the connector <methodname>best_encoder</methodname> helper
1869 After locating the appropriate encoders, the helper function will
1870 call the <methodname>mode_fixup</methodname> encoder and CRTC helper
1871 operations to adjust the requested mode, or reject it completely in
1872 which case an error will be returned to the application. If the new
1873 configuration after mode adjustment is identical to the current
1874 configuration the helper function will return without performing any
1878 If the adjusted mode is identical to the current mode but changes to
1879 the frame buffer need to be applied, the
1880 <function>drm_crtc_helper_set_config</function> function will call
1881 the CRTC <methodname>mode_set_base</methodname> helper operation. If
1882 the adjusted mode differs from the current mode, or if the
1883 <methodname>mode_set_base</methodname> helper operation is not
1884 provided, the helper function performs a full mode set sequence by
1885 calling the <methodname>prepare</methodname>,
1886 <methodname>mode_set</methodname> and
1887 <methodname>commit</methodname> CRTC and encoder helper operations,
1892 <synopsis>void drm_helper_connector_dpms(struct drm_connector *connector, int mode);</synopsis>
1894 The <function>drm_helper_connector_dpms</function> helper function
1895 is a connector <methodname>dpms</methodname> implementation that
1896 tracks power state of connectors. To use the function, drivers must
1897 provide <methodname>dpms</methodname> helper operations for CRTCs
1898 and encoders to apply the DPMS state to the device.
1901 The mid-layer doesn't track the power state of CRTCs and encoders.
1902 The <methodname>dpms</methodname> helper operations can thus be
1903 called with a mode identical to the currently active mode.
1907 <synopsis>int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
1908 uint32_t maxX, uint32_t maxY);</synopsis>
1910 The <function>drm_helper_probe_single_connector_modes</function> helper
1911 function is a connector <methodname>fill_modes</methodname>
1912 implementation that updates the connection status for the connector
1913 and then retrieves a list of modes by calling the connector
1914 <methodname>get_modes</methodname> helper operation.
1917 If the helper operation returns no mode, and if the connector status
1918 is connector_status_connected, standard VESA DMT modes up to
1919 1024x768 are automatically added to the modes list by a call to
1920 <function>drm_add_modes_noedid</function>.
1923 The function then filters out modes larger than
1924 <parameter>max_width</parameter> and <parameter>max_height</parameter>
1925 if specified. It finally calls the optional connector
1926 <methodname>mode_valid</methodname> helper operation for each mode in
1927 the probed list to check whether the mode is valid for the connector.
1933 <title>CRTC Helper Operations</title>
1935 <listitem id="drm-helper-crtc-mode-fixup">
1936 <synopsis>bool (*mode_fixup)(struct drm_crtc *crtc,
1937 const struct drm_display_mode *mode,
1938 struct drm_display_mode *adjusted_mode);</synopsis>
1940 Let CRTCs adjust the requested mode or reject it completely. This
1941 operation returns true if the mode is accepted (possibly after being
1942 adjusted) or false if it is rejected.
1945 The <methodname>mode_fixup</methodname> operation should reject the
1946 mode if it can't reasonably use it. The definition of "reasonable"
1947 is currently fuzzy in this context. One possible behaviour would be
1948 to set the adjusted mode to the panel timings when a fixed-mode
1949 panel is used with hardware capable of scaling. Another behaviour
1950 would be to accept any input mode and adjust it to the closest mode
1951 supported by the hardware (FIXME: This needs to be clarified).
1955 <synopsis>int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
1956 struct drm_framebuffer *old_fb)</synopsis>
1958 Move the CRTC on the current frame buffer (stored in
1959 <literal>crtc->fb</literal>) to position (x,y). Any of the frame
1960 buffer, x position or y position may have been modified.
1963 This helper operation is optional. If not provided, the
1964 <function>drm_crtc_helper_set_config</function> function will fall
1965 back to the <methodname>mode_set</methodname> helper operation.
1968 FIXME: Why are x and y passed as arguments, as they can be accessed
1969 through <literal>crtc->x</literal> and
1970 <literal>crtc->y</literal>?
1974 <synopsis>void (*prepare)(struct drm_crtc *crtc);</synopsis>
1976 Prepare the CRTC for mode setting. This operation is called after
1977 validating the requested mode. Drivers use it to perform
1978 device-specific operations required before setting the new mode.
1982 <synopsis>int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
1983 struct drm_display_mode *adjusted_mode, int x, int y,
1984 struct drm_framebuffer *old_fb);</synopsis>
1986 Set a new mode, position and frame buffer. Depending on the device
1987 requirements, the mode can be stored internally by the driver and
1988 applied in the <methodname>commit</methodname> operation, or
1989 programmed to the hardware immediately.
1992 The <methodname>mode_set</methodname> operation returns 0 on success
1993 or a negative error code if an error occurs.
1997 <synopsis>void (*commit)(struct drm_crtc *crtc);</synopsis>
1999 Commit a mode. This operation is called after setting the new mode.
2000 Upon return the device must use the new mode and be fully
2007 <title>Encoder Helper Operations</title>
2010 <synopsis>bool (*mode_fixup)(struct drm_encoder *encoder,
2011 const struct drm_display_mode *mode,
2012 struct drm_display_mode *adjusted_mode);</synopsis>
2014 Let encoders adjust the requested mode or reject it completely. This
2015 operation returns true if the mode is accepted (possibly after being
2016 adjusted) or false if it is rejected. See the
2017 <link linkend="drm-helper-crtc-mode-fixup">mode_fixup CRTC helper
2018 operation</link> for an explanation of the allowed adjustments.
2022 <synopsis>void (*prepare)(struct drm_encoder *encoder);</synopsis>
2024 Prepare the encoder for mode setting. This operation is called after
2025 validating the requested mode. Drivers use it to perform
2026 device-specific operations required before setting the new mode.
2030 <synopsis>void (*mode_set)(struct drm_encoder *encoder,
2031 struct drm_display_mode *mode,
2032 struct drm_display_mode *adjusted_mode);</synopsis>
2034 Set a new mode. Depending on the device requirements, the mode can
2035 be stored internally by the driver and applied in the
2036 <methodname>commit</methodname> operation, or programmed to the
2037 hardware immediately.
2041 <synopsis>void (*commit)(struct drm_encoder *encoder);</synopsis>
2043 Commit a mode. This operation is called after setting the new mode.
2044 Upon return the device must use the new mode and be fully
2051 <title>Connector Helper Operations</title>
2054 <synopsis>struct drm_encoder *(*best_encoder)(struct drm_connector *connector);</synopsis>
2056 Return a pointer to the best encoder for the connecter. Device that
2057 map connectors to encoders 1:1 simply return the pointer to the
2058 associated encoder. This operation is mandatory.
2062 <synopsis>int (*get_modes)(struct drm_connector *connector);</synopsis>
2064 Fill the connector's <structfield>probed_modes</structfield> list
2065 by parsing EDID data with <function>drm_add_edid_modes</function>,
2066 adding standard VESA DMT modes with <function>drm_add_modes_noedid</function>,
2067 or calling <function>drm_mode_probed_add</function> directly for every
2068 supported mode and return the number of modes it has detected. This
2069 operation is mandatory.
2072 Note that the caller function will automatically add standard VESA
2073 DMT modes up to 1024x768 if the <methodname>get_modes</methodname>
2074 helper operation returns no mode and if the connector status is
2075 connector_status_connected. There is no need to call
2076 <function>drm_add_edid_modes</function> manually in that case.
2079 When adding modes manually the driver creates each mode with a call to
2080 <function>drm_mode_create</function> and must fill the following fields.
2083 <synopsis>__u32 type;</synopsis>
2085 Mode type bitmask, a combination of
2088 <term>DRM_MODE_TYPE_BUILTIN</term>
2089 <listitem><para>not used?</para></listitem>
2092 <term>DRM_MODE_TYPE_CLOCK_C</term>
2093 <listitem><para>not used?</para></listitem>
2096 <term>DRM_MODE_TYPE_CRTC_C</term>
2097 <listitem><para>not used?</para></listitem>
2101 DRM_MODE_TYPE_PREFERRED - The preferred mode for the connector
2104 <para>not used?</para>
2108 <term>DRM_MODE_TYPE_DEFAULT</term>
2109 <listitem><para>not used?</para></listitem>
2112 <term>DRM_MODE_TYPE_USERDEF</term>
2113 <listitem><para>not used?</para></listitem>
2116 <term>DRM_MODE_TYPE_DRIVER</term>
2119 The mode has been created by the driver (as opposed to
2120 to user-created modes).
2125 Drivers must set the DRM_MODE_TYPE_DRIVER bit for all modes they
2126 create, and set the DRM_MODE_TYPE_PREFERRED bit for the preferred
2131 <synopsis>__u32 clock;</synopsis>
2132 <para>Pixel clock frequency in kHz unit</para>
2135 <synopsis>__u16 hdisplay, hsync_start, hsync_end, htotal;
2136 __u16 vdisplay, vsync_start, vsync_end, vtotal;</synopsis>
2137 <para>Horizontal and vertical timing information</para>
2139 Active Front Sync Back
2141 <-----------------------><----------------><-------------><-------------->
2143 //////////////////////|
2144 ////////////////////// |
2145 ////////////////////// |.................. ................
2148 <----- [hv]display ----->
2149 <------------- [hv]sync_start ------------>
2150 <--------------------- [hv]sync_end --------------------->
2151 <-------------------------------- [hv]total ----------------------------->
2155 <synopsis>__u16 hskew;
2156 __u16 vscan;</synopsis>
2157 <para>Unknown</para>
2160 <synopsis>__u32 flags;</synopsis>
2162 Mode flags, a combination of
2165 <term>DRM_MODE_FLAG_PHSYNC</term>
2167 Horizontal sync is active high
2171 <term>DRM_MODE_FLAG_NHSYNC</term>
2173 Horizontal sync is active low
2177 <term>DRM_MODE_FLAG_PVSYNC</term>
2179 Vertical sync is active high
2183 <term>DRM_MODE_FLAG_NVSYNC</term>
2185 Vertical sync is active low
2189 <term>DRM_MODE_FLAG_INTERLACE</term>
2195 <term>DRM_MODE_FLAG_DBLSCAN</term>
2197 Mode uses doublescan
2201 <term>DRM_MODE_FLAG_CSYNC</term>
2203 Mode uses composite sync
2207 <term>DRM_MODE_FLAG_PCSYNC</term>
2209 Composite sync is active high
2213 <term>DRM_MODE_FLAG_NCSYNC</term>
2215 Composite sync is active low
2219 <term>DRM_MODE_FLAG_HSKEW</term>
2221 hskew provided (not used?)
2225 <term>DRM_MODE_FLAG_BCAST</term>
2231 <term>DRM_MODE_FLAG_PIXMUX</term>
2237 <term>DRM_MODE_FLAG_DBLCLK</term>
2243 <term>DRM_MODE_FLAG_CLKDIV2</term>
2251 Note that modes marked with the INTERLACE or DBLSCAN flags will be
2253 <function>drm_helper_probe_single_connector_modes</function> if
2254 the connector's <structfield>interlace_allowed</structfield> or
2255 <structfield>doublescan_allowed</structfield> field is set to 0.
2259 <synopsis>char name[DRM_DISPLAY_MODE_LEN];</synopsis>
2261 Mode name. The driver must call
2262 <function>drm_mode_set_name</function> to fill the mode name from
2263 <structfield>hdisplay</structfield>,
2264 <structfield>vdisplay</structfield> and interlace flag after
2265 filling the corresponding fields.
2271 The <structfield>vrefresh</structfield> value is computed by
2272 <function>drm_helper_probe_single_connector_modes</function>.
2275 When parsing EDID data, <function>drm_add_edid_modes</function> fills the
2276 connector <structfield>display_info</structfield>
2277 <structfield>width_mm</structfield> and
2278 <structfield>height_mm</structfield> fields. When creating modes
2279 manually the <methodname>get_modes</methodname> helper operation must
2280 set the <structfield>display_info</structfield>
2281 <structfield>width_mm</structfield> and
2282 <structfield>height_mm</structfield> fields if they haven't been set
2283 already (for instance at initialization time when a fixed-size panel is
2284 attached to the connector). The mode <structfield>width_mm</structfield>
2285 and <structfield>height_mm</structfield> fields are only used internally
2286 during EDID parsing and should not be set when creating modes manually.
2290 <synopsis>int (*mode_valid)(struct drm_connector *connector,
2291 struct drm_display_mode *mode);</synopsis>
2293 Verify whether a mode is valid for the connector. Return MODE_OK for
2294 supported modes and one of the enum drm_mode_status values (MODE_*)
2295 for unsupported modes. This operation is optional.
2298 As the mode rejection reason is currently not used beside for
2299 immediately removing the unsupported mode, an implementation can
2300 return MODE_BAD regardless of the exact reason why the mode is not
2304 Note that the <methodname>mode_valid</methodname> helper operation is
2305 only called for modes detected by the device, and
2306 <emphasis>not</emphasis> for modes set by the user through the CRTC
2307 <methodname>set_config</methodname> operation.
2313 <title>Atomic Modeset Helper Functions Reference</title>
2315 <title>Overview</title>
2316 !Pdrivers/gpu/drm/drm_atomic_helper.c overview
2319 <title>Implementing Asynchronous Atomic Commit</title>
2320 !Pdrivers/gpu/drm/drm_atomic_helper.c implementing async commit
2323 <title>Atomic State Reset and Initialization</title>
2324 !Pdrivers/gpu/drm/drm_atomic_helper.c atomic state reset and initialization
2326 !Iinclude/drm/drm_atomic_helper.h
2327 !Edrivers/gpu/drm/drm_atomic_helper.c
2330 <title>Modeset Helper Functions Reference</title>
2331 !Iinclude/drm/drm_crtc_helper.h
2332 !Edrivers/gpu/drm/drm_crtc_helper.c
2333 !Pdrivers/gpu/drm/drm_crtc_helper.c overview
2336 <title>Output Probing Helper Functions Reference</title>
2337 !Pdrivers/gpu/drm/drm_probe_helper.c output probing helper overview
2338 !Edrivers/gpu/drm/drm_probe_helper.c
2341 <title>fbdev Helper Functions Reference</title>
2342 !Pdrivers/gpu/drm/drm_fb_helper.c fbdev helpers
2343 !Edrivers/gpu/drm/drm_fb_helper.c
2344 !Iinclude/drm/drm_fb_helper.h
2347 <title>Display Port Helper Functions Reference</title>
2348 !Pdrivers/gpu/drm/drm_dp_helper.c dp helpers
2349 !Iinclude/drm/drm_dp_helper.h
2350 !Edrivers/gpu/drm/drm_dp_helper.c
2353 <title>Display Port MST Helper Functions Reference</title>
2354 !Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper
2355 !Iinclude/drm/drm_dp_mst_helper.h
2356 !Edrivers/gpu/drm/drm_dp_mst_topology.c
2359 <title>MIPI DSI Helper Functions Reference</title>
2360 !Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers
2361 !Iinclude/drm/drm_mipi_dsi.h
2362 !Edrivers/gpu/drm/drm_mipi_dsi.c
2365 <title>EDID Helper Functions Reference</title>
2366 !Edrivers/gpu/drm/drm_edid.c
2369 <title>Rectangle Utilities Reference</title>
2370 !Pinclude/drm/drm_rect.h rect utils
2371 !Iinclude/drm/drm_rect.h
2372 !Edrivers/gpu/drm/drm_rect.c
2375 <title>Flip-work Helper Reference</title>
2376 !Pinclude/drm/drm_flip_work.h flip utils
2377 !Iinclude/drm/drm_flip_work.h
2378 !Edrivers/gpu/drm/drm_flip_work.c
2381 <title>HDMI Infoframes Helper Reference</title>
2383 Strictly speaking this is not a DRM helper library but generally useable
2384 by any driver interfacing with HDMI outputs like v4l or alsa drivers.
2385 But it nicely fits into the overall topic of mode setting helper
2386 libraries and hence is also included here.
2388 !Iinclude/linux/hdmi.h
2389 !Edrivers/video/hdmi.c
2392 <title id="drm-kms-planehelpers">Plane Helper Reference</title>
2393 !Edrivers/gpu/drm/drm_plane_helper.c
2394 !Pdrivers/gpu/drm/drm_plane_helper.c overview
2397 <title>Tile group</title>
2398 !Pdrivers/gpu/drm/drm_crtc.c Tile group
2401 <title>Bridges</title>
2403 <title>Overview</title>
2404 !Pdrivers/gpu/drm/drm_bridge.c overview
2407 <title>Default bridge callback sequence</title>
2408 !Pdrivers/gpu/drm/drm_bridge.c bridge callbacks
2410 !Edrivers/gpu/drm/drm_bridge.c
2414 <!-- Internals: kms properties -->
2416 <sect1 id="drm-kms-properties">
2417 <title>KMS Properties</title>
2419 Drivers may need to expose additional parameters to applications than
2420 those described in the previous sections. KMS supports attaching
2421 properties to CRTCs, connectors and planes and offers a userspace API to
2422 list, get and set the property values.
2425 Properties are identified by a name that uniquely defines the property
2426 purpose, and store an associated value. For all property types except blob
2427 properties the value is a 64-bit unsigned integer.
2430 KMS differentiates between properties and property instances. Drivers
2431 first create properties and then create and associate individual instances
2432 of those properties to objects. A property can be instantiated multiple
2433 times and associated with different objects. Values are stored in property
2434 instances, and all other property information are stored in the property
2435 and shared between all instances of the property.
2438 Every property is created with a type that influences how the KMS core
2439 handles the property. Supported property types are
2442 <term>DRM_MODE_PROP_RANGE</term>
2443 <listitem><para>Range properties report their minimum and maximum
2444 admissible values. The KMS core verifies that values set by
2445 application fit in that range.</para></listitem>
2448 <term>DRM_MODE_PROP_ENUM</term>
2449 <listitem><para>Enumerated properties take a numerical value that
2450 ranges from 0 to the number of enumerated values defined by the
2451 property minus one, and associate a free-formed string name to each
2452 value. Applications can retrieve the list of defined value-name pairs
2453 and use the numerical value to get and set property instance values.
2457 <term>DRM_MODE_PROP_BITMASK</term>
2458 <listitem><para>Bitmask properties are enumeration properties that
2459 additionally restrict all enumerated values to the 0..63 range.
2460 Bitmask property instance values combine one or more of the
2461 enumerated bits defined by the property.</para></listitem>
2464 <term>DRM_MODE_PROP_BLOB</term>
2465 <listitem><para>Blob properties store a binary blob without any format
2466 restriction. The binary blobs are created as KMS standalone objects,
2467 and blob property instance values store the ID of their associated
2469 <para>Blob properties are only used for the connector EDID property
2470 and cannot be created by drivers.</para></listitem>
2475 To create a property drivers call one of the following functions depending
2476 on the property type. All property creation functions take property flags
2477 and name, as well as type-specific arguments.
2480 <synopsis>struct drm_property *drm_property_create_range(struct drm_device *dev, int flags,
2482 uint64_t min, uint64_t max);</synopsis>
2483 <para>Create a range property with the given minimum and maximum
2487 <synopsis>struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags,
2489 const struct drm_prop_enum_list *props,
2490 int num_values);</synopsis>
2491 <para>Create an enumerated property. The <parameter>props</parameter>
2492 argument points to an array of <parameter>num_values</parameter>
2493 value-name pairs.</para>
2496 <synopsis>struct drm_property *drm_property_create_bitmask(struct drm_device *dev,
2497 int flags, const char *name,
2498 const struct drm_prop_enum_list *props,
2499 int num_values);</synopsis>
2500 <para>Create a bitmask property. The <parameter>props</parameter>
2501 argument points to an array of <parameter>num_values</parameter>
2502 value-name pairs.</para>
2507 Properties can additionally be created as immutable, in which case they
2508 will be read-only for applications but can be modified by the driver. To
2509 create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE
2510 flag at property creation time.
2513 When no array of value-name pairs is readily available at property
2514 creation time for enumerated or range properties, drivers can create
2515 the property using the <function>drm_property_create</function> function
2516 and manually add enumeration value-name pairs by calling the
2517 <function>drm_property_add_enum</function> function. Care must be taken to
2518 properly specify the property type through the <parameter>flags</parameter>
2522 After creating properties drivers can attach property instances to CRTC,
2523 connector and plane objects by calling the
2524 <function>drm_object_attach_property</function>. The function takes a
2525 pointer to the target object, a pointer to the previously created property
2526 and an initial instance value.
2529 <title>Existing KMS Properties</title>
2531 The following table gives description of drm properties exposed by various
2534 <table border="1" cellpadding="0" cellspacing="0">
2536 <tr style="font-weight: bold;">
2537 <td valign="top" >Owner Module/Drivers</td>
2538 <td valign="top" >Group</td>
2539 <td valign="top" >Property Name</td>
2540 <td valign="top" >Type</td>
2541 <td valign="top" >Property Values</td>
2542 <td valign="top" >Object attached</td>
2543 <td valign="top" >Description/Restrictions</td>
2546 <td rowspan="37" valign="top" >DRM</td>
2547 <td valign="top" >Generic</td>
2548 <td valign="top" >“rotation”</td>
2549 <td valign="top" >BITMASK</td>
2550 <td valign="top" >{ 0, "rotate-0" },
2552 { 2, "rotate-180" },
2553 { 3, "rotate-270" },
2555 { 5, "reflect-y" }</td>
2556 <td valign="top" >CRTC, Plane</td>
2557 <td valign="top" >rotate-(degrees) rotates the image by the specified amount in degrees
2558 in counter clockwise direction. reflect-x and reflect-y reflects the
2559 image along the specified axis prior to rotation</td>
2562 <td rowspan="5" valign="top" >Connector</td>
2563 <td valign="top" >“EDID”</td>
2564 <td valign="top" >BLOB | IMMUTABLE</td>
2565 <td valign="top" >0</td>
2566 <td valign="top" >Connector</td>
2567 <td valign="top" >Contains id of edid blob ptr object.</td>
2570 <td valign="top" >“DPMS”</td>
2571 <td valign="top" >ENUM</td>
2572 <td valign="top" >{ “On”, “Standby”, “Suspend”, “Off” }</td>
2573 <td valign="top" >Connector</td>
2574 <td valign="top" >Contains DPMS operation mode value.</td>
2577 <td valign="top" >“PATH”</td>
2578 <td valign="top" >BLOB | IMMUTABLE</td>
2579 <td valign="top" >0</td>
2580 <td valign="top" >Connector</td>
2581 <td valign="top" >Contains topology path to a connector.</td>
2584 <td valign="top" >“TILE”</td>
2585 <td valign="top" >BLOB | IMMUTABLE</td>
2586 <td valign="top" >0</td>
2587 <td valign="top" >Connector</td>
2588 <td valign="top" >Contains tiling information for a connector.</td>
2591 <td valign="top" >“CRTC_ID”</td>
2592 <td valign="top" >OBJECT</td>
2593 <td valign="top" >DRM_MODE_OBJECT_CRTC</td>
2594 <td valign="top" >Connector</td>
2595 <td valign="top" >CRTC that connector is attached to (atomic)</td>
2598 <td rowspan="11" valign="top" >Plane</td>
2599 <td valign="top" >“type”</td>
2600 <td valign="top" >ENUM | IMMUTABLE</td>
2601 <td valign="top" >{ "Overlay", "Primary", "Cursor" }</td>
2602 <td valign="top" >Plane</td>
2603 <td valign="top" >Plane type</td>
2606 <td valign="top" >“SRC_X”</td>
2607 <td valign="top" >RANGE</td>
2608 <td valign="top" >Min=0, Max=UINT_MAX</td>
2609 <td valign="top" >Plane</td>
2610 <td valign="top" >Scanout source x coordinate in 16.16 fixed point (atomic)</td>
2613 <td valign="top" >“SRC_Y”</td>
2614 <td valign="top" >RANGE</td>
2615 <td valign="top" >Min=0, Max=UINT_MAX</td>
2616 <td valign="top" >Plane</td>
2617 <td valign="top" >Scanout source y coordinate in 16.16 fixed point (atomic)</td>
2620 <td valign="top" >“SRC_W”</td>
2621 <td valign="top" >RANGE</td>
2622 <td valign="top" >Min=0, Max=UINT_MAX</td>
2623 <td valign="top" >Plane</td>
2624 <td valign="top" >Scanout source width in 16.16 fixed point (atomic)</td>
2627 <td valign="top" >“SRC_H”</td>
2628 <td valign="top" >RANGE</td>
2629 <td valign="top" >Min=0, Max=UINT_MAX</td>
2630 <td valign="top" >Plane</td>
2631 <td valign="top" >Scanout source height in 16.16 fixed point (atomic)</td>
2634 <td valign="top" >“CRTC_X”</td>
2635 <td valign="top" >SIGNED_RANGE</td>
2636 <td valign="top" >Min=INT_MIN, Max=INT_MAX</td>
2637 <td valign="top" >Plane</td>
2638 <td valign="top" >Scanout CRTC (destination) x coordinate (atomic)</td>
2641 <td valign="top" >“CRTC_Y”</td>
2642 <td valign="top" >SIGNED_RANGE</td>
2643 <td valign="top" >Min=INT_MIN, Max=INT_MAX</td>
2644 <td valign="top" >Plane</td>
2645 <td valign="top" >Scanout CRTC (destination) y coordinate (atomic)</td>
2648 <td valign="top" >“CRTC_W”</td>
2649 <td valign="top" >RANGE</td>
2650 <td valign="top" >Min=0, Max=UINT_MAX</td>
2651 <td valign="top" >Plane</td>
2652 <td valign="top" >Scanout CRTC (destination) width (atomic)</td>
2655 <td valign="top" >“CRTC_H”</td>
2656 <td valign="top" >RANGE</td>
2657 <td valign="top" >Min=0, Max=UINT_MAX</td>
2658 <td valign="top" >Plane</td>
2659 <td valign="top" >Scanout CRTC (destination) height (atomic)</td>
2662 <td valign="top" >“FB_ID”</td>
2663 <td valign="top" >OBJECT</td>
2664 <td valign="top" >DRM_MODE_OBJECT_FB</td>
2665 <td valign="top" >Plane</td>
2666 <td valign="top" >Scanout framebuffer (atomic)</td>
2669 <td valign="top" >“CRTC_ID”</td>
2670 <td valign="top" >OBJECT</td>
2671 <td valign="top" >DRM_MODE_OBJECT_CRTC</td>
2672 <td valign="top" >Plane</td>
2673 <td valign="top" >CRTC that plane is attached to (atomic)</td>
2676 <td rowspan="2" valign="top" >DVI-I</td>
2677 <td valign="top" >“subconnector”</td>
2678 <td valign="top" >ENUM</td>
2679 <td valign="top" >{ “Unknown”, “DVI-D”, “DVI-A” }</td>
2680 <td valign="top" >Connector</td>
2681 <td valign="top" >TBD</td>
2684 <td valign="top" >“select subconnector”</td>
2685 <td valign="top" >ENUM</td>
2686 <td valign="top" >{ “Automatic”, “DVI-D”, “DVI-A” }</td>
2687 <td valign="top" >Connector</td>
2688 <td valign="top" >TBD</td>
2691 <td rowspan="13" valign="top" >TV</td>
2692 <td valign="top" >“subconnector”</td>
2693 <td valign="top" >ENUM</td>
2694 <td valign="top" >{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }</td>
2695 <td valign="top" >Connector</td>
2696 <td valign="top" >TBD</td>
2699 <td valign="top" >“select subconnector”</td>
2700 <td valign="top" >ENUM</td>
2701 <td valign="top" >{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }</td>
2702 <td valign="top" >Connector</td>
2703 <td valign="top" >TBD</td>
2706 <td valign="top" >“mode”</td>
2707 <td valign="top" >ENUM</td>
2708 <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
2709 <td valign="top" >Connector</td>
2710 <td valign="top" >TBD</td>
2713 <td valign="top" >“left margin”</td>
2714 <td valign="top" >RANGE</td>
2715 <td valign="top" >Min=0, Max=100</td>
2716 <td valign="top" >Connector</td>
2717 <td valign="top" >TBD</td>
2720 <td valign="top" >“right margin”</td>
2721 <td valign="top" >RANGE</td>
2722 <td valign="top" >Min=0, Max=100</td>
2723 <td valign="top" >Connector</td>
2724 <td valign="top" >TBD</td>
2727 <td valign="top" >“top margin”</td>
2728 <td valign="top" >RANGE</td>
2729 <td valign="top" >Min=0, Max=100</td>
2730 <td valign="top" >Connector</td>
2731 <td valign="top" >TBD</td>
2734 <td valign="top" >“bottom margin”</td>
2735 <td valign="top" >RANGE</td>
2736 <td valign="top" >Min=0, Max=100</td>
2737 <td valign="top" >Connector</td>
2738 <td valign="top" >TBD</td>
2741 <td valign="top" >“brightness”</td>
2742 <td valign="top" >RANGE</td>
2743 <td valign="top" >Min=0, Max=100</td>
2744 <td valign="top" >Connector</td>
2745 <td valign="top" >TBD</td>
2748 <td valign="top" >“contrast”</td>
2749 <td valign="top" >RANGE</td>
2750 <td valign="top" >Min=0, Max=100</td>
2751 <td valign="top" >Connector</td>
2752 <td valign="top" >TBD</td>
2755 <td valign="top" >“flicker reduction”</td>
2756 <td valign="top" >RANGE</td>
2757 <td valign="top" >Min=0, Max=100</td>
2758 <td valign="top" >Connector</td>
2759 <td valign="top" >TBD</td>
2762 <td valign="top" >“overscan”</td>
2763 <td valign="top" >RANGE</td>
2764 <td valign="top" >Min=0, Max=100</td>
2765 <td valign="top" >Connector</td>
2766 <td valign="top" >TBD</td>
2769 <td valign="top" >“saturation”</td>
2770 <td valign="top" >RANGE</td>
2771 <td valign="top" >Min=0, Max=100</td>
2772 <td valign="top" >Connector</td>
2773 <td valign="top" >TBD</td>
2776 <td valign="top" >“hue”</td>
2777 <td valign="top" >RANGE</td>
2778 <td valign="top" >Min=0, Max=100</td>
2779 <td valign="top" >Connector</td>
2780 <td valign="top" >TBD</td>
2783 <td rowspan="2" valign="top" >Virtual GPU</td>
2784 <td valign="top" >“suggested X”</td>
2785 <td valign="top" >RANGE</td>
2786 <td valign="top" >Min=0, Max=0xffffffff</td>
2787 <td valign="top" >Connector</td>
2788 <td valign="top" >property to suggest an X offset for a connector</td>
2791 <td valign="top" >“suggested Y”</td>
2792 <td valign="top" >RANGE</td>
2793 <td valign="top" >Min=0, Max=0xffffffff</td>
2794 <td valign="top" >Connector</td>
2795 <td valign="top" >property to suggest an Y offset for a connector</td>
2798 <td rowspan="3" valign="top" >Optional</td>
2799 <td valign="top" >“scaling mode”</td>
2800 <td valign="top" >ENUM</td>
2801 <td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td>
2802 <td valign="top" >Connector</td>
2803 <td valign="top" >TBD</td>
2806 <td valign="top" >"aspect ratio"</td>
2807 <td valign="top" >ENUM</td>
2808 <td valign="top" >{ "None", "4:3", "16:9" }</td>
2809 <td valign="top" >Connector</td>
2810 <td valign="top" >DRM property to set aspect ratio from user space app.
2811 This enum is made generic to allow addition of custom aspect
2815 <td valign="top" >“dirty”</td>
2816 <td valign="top" >ENUM | IMMUTABLE</td>
2817 <td valign="top" >{ "Off", "On", "Annotate" }</td>
2818 <td valign="top" >Connector</td>
2819 <td valign="top" >TBD</td>
2822 <td rowspan="20" valign="top" >i915</td>
2823 <td rowspan="2" valign="top" >Generic</td>
2824 <td valign="top" >"Broadcast RGB"</td>
2825 <td valign="top" >ENUM</td>
2826 <td valign="top" >{ "Automatic", "Full", "Limited 16:235" }</td>
2827 <td valign="top" >Connector</td>
2828 <td valign="top" >TBD</td>
2831 <td valign="top" >“audio”</td>
2832 <td valign="top" >ENUM</td>
2833 <td valign="top" >{ "force-dvi", "off", "auto", "on" }</td>
2834 <td valign="top" >Connector</td>
2835 <td valign="top" >TBD</td>
2838 <td rowspan="17" valign="top" >SDVO-TV</td>
2839 <td valign="top" >“mode”</td>
2840 <td valign="top" >ENUM</td>
2841 <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
2842 <td valign="top" >Connector</td>
2843 <td valign="top" >TBD</td>
2846 <td valign="top" >"left_margin"</td>
2847 <td valign="top" >RANGE</td>
2848 <td valign="top" >Min=0, Max= SDVO dependent</td>
2849 <td valign="top" >Connector</td>
2850 <td valign="top" >TBD</td>
2853 <td valign="top" >"right_margin"</td>
2854 <td valign="top" >RANGE</td>
2855 <td valign="top" >Min=0, Max= SDVO dependent</td>
2856 <td valign="top" >Connector</td>
2857 <td valign="top" >TBD</td>
2860 <td valign="top" >"top_margin"</td>
2861 <td valign="top" >RANGE</td>
2862 <td valign="top" >Min=0, Max= SDVO dependent</td>
2863 <td valign="top" >Connector</td>
2864 <td valign="top" >TBD</td>
2867 <td valign="top" >"bottom_margin"</td>
2868 <td valign="top" >RANGE</td>
2869 <td valign="top" >Min=0, Max= SDVO dependent</td>
2870 <td valign="top" >Connector</td>
2871 <td valign="top" >TBD</td>
2874 <td valign="top" >“hpos”</td>
2875 <td valign="top" >RANGE</td>
2876 <td valign="top" >Min=0, Max= SDVO dependent</td>
2877 <td valign="top" >Connector</td>
2878 <td valign="top" >TBD</td>
2881 <td valign="top" >“vpos”</td>
2882 <td valign="top" >RANGE</td>
2883 <td valign="top" >Min=0, Max= SDVO dependent</td>
2884 <td valign="top" >Connector</td>
2885 <td valign="top" >TBD</td>
2888 <td valign="top" >“contrast”</td>
2889 <td valign="top" >RANGE</td>
2890 <td valign="top" >Min=0, Max= SDVO dependent</td>
2891 <td valign="top" >Connector</td>
2892 <td valign="top" >TBD</td>
2895 <td valign="top" >“saturation”</td>
2896 <td valign="top" >RANGE</td>
2897 <td valign="top" >Min=0, Max= SDVO dependent</td>
2898 <td valign="top" >Connector</td>
2899 <td valign="top" >TBD</td>
2902 <td valign="top" >“hue”</td>
2903 <td valign="top" >RANGE</td>
2904 <td valign="top" >Min=0, Max= SDVO dependent</td>
2905 <td valign="top" >Connector</td>
2906 <td valign="top" >TBD</td>
2909 <td valign="top" >“sharpness”</td>
2910 <td valign="top" >RANGE</td>
2911 <td valign="top" >Min=0, Max= SDVO dependent</td>
2912 <td valign="top" >Connector</td>
2913 <td valign="top" >TBD</td>
2916 <td valign="top" >“flicker_filter”</td>
2917 <td valign="top" >RANGE</td>
2918 <td valign="top" >Min=0, Max= SDVO dependent</td>
2919 <td valign="top" >Connector</td>
2920 <td valign="top" >TBD</td>
2923 <td valign="top" >“flicker_filter_adaptive”</td>
2924 <td valign="top" >RANGE</td>
2925 <td valign="top" >Min=0, Max= SDVO dependent</td>
2926 <td valign="top" >Connector</td>
2927 <td valign="top" >TBD</td>
2930 <td valign="top" >“flicker_filter_2d”</td>
2931 <td valign="top" >RANGE</td>
2932 <td valign="top" >Min=0, Max= SDVO dependent</td>
2933 <td valign="top" >Connector</td>
2934 <td valign="top" >TBD</td>
2937 <td valign="top" >“tv_chroma_filter”</td>
2938 <td valign="top" >RANGE</td>
2939 <td valign="top" >Min=0, Max= SDVO dependent</td>
2940 <td valign="top" >Connector</td>
2941 <td valign="top" >TBD</td>
2944 <td valign="top" >“tv_luma_filter”</td>
2945 <td valign="top" >RANGE</td>
2946 <td valign="top" >Min=0, Max= SDVO dependent</td>
2947 <td valign="top" >Connector</td>
2948 <td valign="top" >TBD</td>
2951 <td valign="top" >“dot_crawl”</td>
2952 <td valign="top" >RANGE</td>
2953 <td valign="top" >Min=0, Max=1</td>
2954 <td valign="top" >Connector</td>
2955 <td valign="top" >TBD</td>
2958 <td valign="top" >SDVO-TV/LVDS</td>
2959 <td valign="top" >“brightness”</td>
2960 <td valign="top" >RANGE</td>
2961 <td valign="top" >Min=0, Max= SDVO dependent</td>
2962 <td valign="top" >Connector</td>
2963 <td valign="top" >TBD</td>
2966 <td rowspan="2" valign="top" >CDV gma-500</td>
2967 <td rowspan="2" valign="top" >Generic</td>
2968 <td valign="top" >"Broadcast RGB"</td>
2969 <td valign="top" >ENUM</td>
2970 <td valign="top" >{ “Full”, “Limited 16:235” }</td>
2971 <td valign="top" >Connector</td>
2972 <td valign="top" >TBD</td>
2975 <td valign="top" >"Broadcast RGB"</td>
2976 <td valign="top" >ENUM</td>
2977 <td valign="top" >{ “off”, “auto”, “on” }</td>
2978 <td valign="top" >Connector</td>
2979 <td valign="top" >TBD</td>
2982 <td rowspan="19" valign="top" >Poulsbo</td>
2983 <td rowspan="1" valign="top" >Generic</td>
2984 <td valign="top" >“backlight”</td>
2985 <td valign="top" >RANGE</td>
2986 <td valign="top" >Min=0, Max=100</td>
2987 <td valign="top" >Connector</td>
2988 <td valign="top" >TBD</td>
2991 <td rowspan="17" valign="top" >SDVO-TV</td>
2992 <td valign="top" >“mode”</td>
2993 <td valign="top" >ENUM</td>
2994 <td valign="top" >{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.</td>
2995 <td valign="top" >Connector</td>
2996 <td valign="top" >TBD</td>
2999 <td valign="top" >"left_margin"</td>
3000 <td valign="top" >RANGE</td>
3001 <td valign="top" >Min=0, Max= SDVO dependent</td>
3002 <td valign="top" >Connector</td>
3003 <td valign="top" >TBD</td>
3006 <td valign="top" >"right_margin"</td>
3007 <td valign="top" >RANGE</td>
3008 <td valign="top" >Min=0, Max= SDVO dependent</td>
3009 <td valign="top" >Connector</td>
3010 <td valign="top" >TBD</td>
3013 <td valign="top" >"top_margin"</td>
3014 <td valign="top" >RANGE</td>
3015 <td valign="top" >Min=0, Max= SDVO dependent</td>
3016 <td valign="top" >Connector</td>
3017 <td valign="top" >TBD</td>
3020 <td valign="top" >"bottom_margin"</td>
3021 <td valign="top" >RANGE</td>
3022 <td valign="top" >Min=0, Max= SDVO dependent</td>
3023 <td valign="top" >Connector</td>
3024 <td valign="top" >TBD</td>
3027 <td valign="top" >“hpos”</td>
3028 <td valign="top" >RANGE</td>
3029 <td valign="top" >Min=0, Max= SDVO dependent</td>
3030 <td valign="top" >Connector</td>
3031 <td valign="top" >TBD</td>
3034 <td valign="top" >“vpos”</td>
3035 <td valign="top" >RANGE</td>
3036 <td valign="top" >Min=0, Max= SDVO dependent</td>
3037 <td valign="top" >Connector</td>
3038 <td valign="top" >TBD</td>
3041 <td valign="top" >“contrast”</td>
3042 <td valign="top" >RANGE</td>
3043 <td valign="top" >Min=0, Max= SDVO dependent</td>
3044 <td valign="top" >Connector</td>
3045 <td valign="top" >TBD</td>
3048 <td valign="top" >“saturation”</td>
3049 <td valign="top" >RANGE</td>
3050 <td valign="top" >Min=0, Max= SDVO dependent</td>
3051 <td valign="top" >Connector</td>
3052 <td valign="top" >TBD</td>
3055 <td valign="top" >“hue”</td>
3056 <td valign="top" >RANGE</td>
3057 <td valign="top" >Min=0, Max= SDVO dependent</td>
3058 <td valign="top" >Connector</td>
3059 <td valign="top" >TBD</td>
3062 <td valign="top" >“sharpness”</td>
3063 <td valign="top" >RANGE</td>
3064 <td valign="top" >Min=0, Max= SDVO dependent</td>
3065 <td valign="top" >Connector</td>
3066 <td valign="top" >TBD</td>
3069 <td valign="top" >“flicker_filter”</td>
3070 <td valign="top" >RANGE</td>
3071 <td valign="top" >Min=0, Max= SDVO dependent</td>
3072 <td valign="top" >Connector</td>
3073 <td valign="top" >TBD</td>
3076 <td valign="top" >“flicker_filter_adaptive”</td>
3077 <td valign="top" >RANGE</td>
3078 <td valign="top" >Min=0, Max= SDVO dependent</td>
3079 <td valign="top" >Connector</td>
3080 <td valign="top" >TBD</td>
3083 <td valign="top" >“flicker_filter_2d”</td>
3084 <td valign="top" >RANGE</td>
3085 <td valign="top" >Min=0, Max= SDVO dependent</td>
3086 <td valign="top" >Connector</td>
3087 <td valign="top" >TBD</td>
3090 <td valign="top" >“tv_chroma_filter”</td>
3091 <td valign="top" >RANGE</td>
3092 <td valign="top" >Min=0, Max= SDVO dependent</td>
3093 <td valign="top" >Connector</td>
3094 <td valign="top" >TBD</td>
3097 <td valign="top" >“tv_luma_filter”</td>
3098 <td valign="top" >RANGE</td>
3099 <td valign="top" >Min=0, Max= SDVO dependent</td>
3100 <td valign="top" >Connector</td>
3101 <td valign="top" >TBD</td>
3104 <td valign="top" >“dot_crawl”</td>
3105 <td valign="top" >RANGE</td>
3106 <td valign="top" >Min=0, Max=1</td>
3107 <td valign="top" >Connector</td>
3108 <td valign="top" >TBD</td>
3111 <td valign="top" >SDVO-TV/LVDS</td>
3112 <td valign="top" >“brightness”</td>
3113 <td valign="top" >RANGE</td>
3114 <td valign="top" >Min=0, Max= SDVO dependent</td>
3115 <td valign="top" >Connector</td>
3116 <td valign="top" >TBD</td>
3119 <td rowspan="11" valign="top" >armada</td>
3120 <td rowspan="2" valign="top" >CRTC</td>
3121 <td valign="top" >"CSC_YUV"</td>
3122 <td valign="top" >ENUM</td>
3123 <td valign="top" >{ "Auto" , "CCIR601", "CCIR709" }</td>
3124 <td valign="top" >CRTC</td>
3125 <td valign="top" >TBD</td>
3128 <td valign="top" >"CSC_RGB"</td>
3129 <td valign="top" >ENUM</td>
3130 <td valign="top" >{ "Auto", "Computer system", "Studio" }</td>
3131 <td valign="top" >CRTC</td>
3132 <td valign="top" >TBD</td>
3135 <td rowspan="9" valign="top" >Overlay</td>
3136 <td valign="top" >"colorkey"</td>
3137 <td valign="top" >RANGE</td>
3138 <td valign="top" >Min=0, Max=0xffffff</td>
3139 <td valign="top" >Plane</td>
3140 <td valign="top" >TBD</td>
3143 <td valign="top" >"colorkey_min"</td>
3144 <td valign="top" >RANGE</td>
3145 <td valign="top" >Min=0, Max=0xffffff</td>
3146 <td valign="top" >Plane</td>
3147 <td valign="top" >TBD</td>
3150 <td valign="top" >"colorkey_max"</td>
3151 <td valign="top" >RANGE</td>
3152 <td valign="top" >Min=0, Max=0xffffff</td>
3153 <td valign="top" >Plane</td>
3154 <td valign="top" >TBD</td>
3157 <td valign="top" >"colorkey_val"</td>
3158 <td valign="top" >RANGE</td>
3159 <td valign="top" >Min=0, Max=0xffffff</td>
3160 <td valign="top" >Plane</td>
3161 <td valign="top" >TBD</td>
3164 <td valign="top" >"colorkey_alpha"</td>
3165 <td valign="top" >RANGE</td>
3166 <td valign="top" >Min=0, Max=0xffffff</td>
3167 <td valign="top" >Plane</td>
3168 <td valign="top" >TBD</td>
3171 <td valign="top" >"colorkey_mode"</td>
3172 <td valign="top" >ENUM</td>
3173 <td valign="top" >{ "disabled", "Y component", "U component"
3174 , "V component", "RGB", “R component", "G component", "B component" }</td>
3175 <td valign="top" >Plane</td>
3176 <td valign="top" >TBD</td>
3179 <td valign="top" >"brightness"</td>
3180 <td valign="top" >RANGE</td>
3181 <td valign="top" >Min=0, Max=256 + 255</td>
3182 <td valign="top" >Plane</td>
3183 <td valign="top" >TBD</td>
3186 <td valign="top" >"contrast"</td>
3187 <td valign="top" >RANGE</td>
3188 <td valign="top" >Min=0, Max=0x7fff</td>
3189 <td valign="top" >Plane</td>
3190 <td valign="top" >TBD</td>
3193 <td valign="top" >"saturation"</td>
3194 <td valign="top" >RANGE</td>
3195 <td valign="top" >Min=0, Max=0x7fff</td>
3196 <td valign="top" >Plane</td>
3197 <td valign="top" >TBD</td>
3200 <td rowspan="2" valign="top" >exynos</td>
3201 <td valign="top" >CRTC</td>
3202 <td valign="top" >“mode”</td>
3203 <td valign="top" >ENUM</td>
3204 <td valign="top" >{ "normal", "blank" }</td>
3205 <td valign="top" >CRTC</td>
3206 <td valign="top" >TBD</td>
3209 <td valign="top" >Overlay</td>
3210 <td valign="top" >“zpos”</td>
3211 <td valign="top" >RANGE</td>
3212 <td valign="top" >Min=0, Max=MAX_PLANE-1</td>
3213 <td valign="top" >Plane</td>
3214 <td valign="top" >TBD</td>
3217 <td rowspan="2" valign="top" >i2c/ch7006_drv</td>
3218 <td valign="top" >Generic</td>
3219 <td valign="top" >“scale”</td>
3220 <td valign="top" >RANGE</td>
3221 <td valign="top" >Min=0, Max=2</td>
3222 <td valign="top" >Connector</td>
3223 <td valign="top" >TBD</td>
3226 <td rowspan="1" valign="top" >TV</td>
3227 <td valign="top" >“mode”</td>
3228 <td valign="top" >ENUM</td>
3229 <td valign="top" >{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc"
3230 , "PAL-60", "NTSC-M", "NTSC-J" }</td>
3231 <td valign="top" >Connector</td>
3232 <td valign="top" >TBD</td>
3235 <td rowspan="15" valign="top" >nouveau</td>
3236 <td rowspan="6" valign="top" >NV10 Overlay</td>
3237 <td valign="top" >"colorkey"</td>
3238 <td valign="top" >RANGE</td>
3239 <td valign="top" >Min=0, Max=0x01ffffff</td>
3240 <td valign="top" >Plane</td>
3241 <td valign="top" >TBD</td>
3244 <td valign="top" >“contrast”</td>
3245 <td valign="top" >RANGE</td>
3246 <td valign="top" >Min=0, Max=8192-1</td>
3247 <td valign="top" >Plane</td>
3248 <td valign="top" >TBD</td>
3251 <td valign="top" >“brightness”</td>
3252 <td valign="top" >RANGE</td>
3253 <td valign="top" >Min=0, Max=1024</td>
3254 <td valign="top" >Plane</td>
3255 <td valign="top" >TBD</td>
3258 <td valign="top" >“hue”</td>
3259 <td valign="top" >RANGE</td>
3260 <td valign="top" >Min=0, Max=359</td>
3261 <td valign="top" >Plane</td>
3262 <td valign="top" >TBD</td>
3265 <td valign="top" >“saturation”</td>
3266 <td valign="top" >RANGE</td>
3267 <td valign="top" >Min=0, Max=8192-1</td>
3268 <td valign="top" >Plane</td>
3269 <td valign="top" >TBD</td>
3272 <td valign="top" >“iturbt_709”</td>
3273 <td valign="top" >RANGE</td>
3274 <td valign="top" >Min=0, Max=1</td>
3275 <td valign="top" >Plane</td>
3276 <td valign="top" >TBD</td>
3279 <td rowspan="2" valign="top" >Nv04 Overlay</td>
3280 <td valign="top" >“colorkey”</td>
3281 <td valign="top" >RANGE</td>
3282 <td valign="top" >Min=0, Max=0x01ffffff</td>
3283 <td valign="top" >Plane</td>
3284 <td valign="top" >TBD</td>
3287 <td valign="top" >“brightness”</td>
3288 <td valign="top" >RANGE</td>
3289 <td valign="top" >Min=0, Max=1024</td>
3290 <td valign="top" >Plane</td>
3291 <td valign="top" >TBD</td>
3294 <td rowspan="7" valign="top" >Display</td>
3295 <td valign="top" >“dithering mode”</td>
3296 <td valign="top" >ENUM</td>
3297 <td valign="top" >{ "auto", "off", "on" }</td>
3298 <td valign="top" >Connector</td>
3299 <td valign="top" >TBD</td>
3302 <td valign="top" >“dithering depth”</td>
3303 <td valign="top" >ENUM</td>
3304 <td valign="top" >{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }</td>
3305 <td valign="top" >Connector</td>
3306 <td valign="top" >TBD</td>
3309 <td valign="top" >“underscan”</td>
3310 <td valign="top" >ENUM</td>
3311 <td valign="top" >{ "auto", "6 bpc", "8 bpc" }</td>
3312 <td valign="top" >Connector</td>
3313 <td valign="top" >TBD</td>
3316 <td valign="top" >“underscan hborder”</td>
3317 <td valign="top" >RANGE</td>
3318 <td valign="top" >Min=0, Max=128</td>
3319 <td valign="top" >Connector</td>
3320 <td valign="top" >TBD</td>
3323 <td valign="top" >“underscan vborder”</td>
3324 <td valign="top" >RANGE</td>
3325 <td valign="top" >Min=0, Max=128</td>
3326 <td valign="top" >Connector</td>
3327 <td valign="top" >TBD</td>
3330 <td valign="top" >“vibrant hue”</td>
3331 <td valign="top" >RANGE</td>
3332 <td valign="top" >Min=0, Max=180</td>
3333 <td valign="top" >Connector</td>
3334 <td valign="top" >TBD</td>
3337 <td valign="top" >“color vibrance”</td>
3338 <td valign="top" >RANGE</td>
3339 <td valign="top" >Min=0, Max=200</td>
3340 <td valign="top" >Connector</td>
3341 <td valign="top" >TBD</td>
3344 <td valign="top" >omap</td>
3345 <td valign="top" >Generic</td>
3346 <td valign="top" >“zorder”</td>
3347 <td valign="top" >RANGE</td>
3348 <td valign="top" >Min=0, Max=3</td>
3349 <td valign="top" >CRTC, Plane</td>
3350 <td valign="top" >TBD</td>
3353 <td valign="top" >qxl</td>
3354 <td valign="top" >Generic</td>
3355 <td valign="top" >“hotplug_mode_update"</td>
3356 <td valign="top" >RANGE</td>
3357 <td valign="top" >Min=0, Max=1</td>
3358 <td valign="top" >Connector</td>
3359 <td valign="top" >TBD</td>
3362 <td rowspan="9" valign="top" >radeon</td>
3363 <td valign="top" >DVI-I</td>
3364 <td valign="top" >“coherent”</td>
3365 <td valign="top" >RANGE</td>
3366 <td valign="top" >Min=0, Max=1</td>
3367 <td valign="top" >Connector</td>
3368 <td valign="top" >TBD</td>
3371 <td valign="top" >DAC enable load detect</td>
3372 <td valign="top" >“load detection”</td>
3373 <td valign="top" >RANGE</td>
3374 <td valign="top" >Min=0, Max=1</td>
3375 <td valign="top" >Connector</td>
3376 <td valign="top" >TBD</td>
3379 <td valign="top" >TV Standard</td>
3380 <td valign="top" >"tv standard"</td>
3381 <td valign="top" >ENUM</td>
3382 <td valign="top" >{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j"
3383 , "scart-pal", "pal-cn", "secam" }</td>
3384 <td valign="top" >Connector</td>
3385 <td valign="top" >TBD</td>
3388 <td valign="top" >legacy TMDS PLL detect</td>
3389 <td valign="top" >"tmds_pll"</td>
3390 <td valign="top" >ENUM</td>
3391 <td valign="top" >{ "driver", "bios" }</td>
3392 <td valign="top" >-</td>
3393 <td valign="top" >TBD</td>
3396 <td rowspan="3" valign="top" >Underscan</td>
3397 <td valign="top" >"underscan"</td>
3398 <td valign="top" >ENUM</td>
3399 <td valign="top" >{ "off", "on", "auto" }</td>
3400 <td valign="top" >Connector</td>
3401 <td valign="top" >TBD</td>
3404 <td valign="top" >"underscan hborder"</td>
3405 <td valign="top" >RANGE</td>
3406 <td valign="top" >Min=0, Max=128</td>
3407 <td valign="top" >Connector</td>
3408 <td valign="top" >TBD</td>
3411 <td valign="top" >"underscan vborder"</td>
3412 <td valign="top" >RANGE</td>
3413 <td valign="top" >Min=0, Max=128</td>
3414 <td valign="top" >Connector</td>
3415 <td valign="top" >TBD</td>
3418 <td valign="top" >Audio</td>
3419 <td valign="top" >“audio”</td>
3420 <td valign="top" >ENUM</td>
3421 <td valign="top" >{ "off", "on", "auto" }</td>
3422 <td valign="top" >Connector</td>
3423 <td valign="top" >TBD</td>
3426 <td valign="top" >FMT Dithering</td>
3427 <td valign="top" >“dither”</td>
3428 <td valign="top" >ENUM</td>
3429 <td valign="top" >{ "off", "on" }</td>
3430 <td valign="top" >Connector</td>
3431 <td valign="top" >TBD</td>
3434 <td rowspan="3" valign="top" >rcar-du</td>
3435 <td rowspan="3" valign="top" >Generic</td>
3436 <td valign="top" >"alpha"</td>
3437 <td valign="top" >RANGE</td>
3438 <td valign="top" >Min=0, Max=255</td>
3439 <td valign="top" >Plane</td>
3440 <td valign="top" >TBD</td>
3443 <td valign="top" >"colorkey"</td>
3444 <td valign="top" >RANGE</td>
3445 <td valign="top" >Min=0, Max=0x01ffffff</td>
3446 <td valign="top" >Plane</td>
3447 <td valign="top" >TBD</td>
3450 <td valign="top" >"zpos"</td>
3451 <td valign="top" >RANGE</td>
3452 <td valign="top" >Min=1, Max=7</td>
3453 <td valign="top" >Plane</td>
3454 <td valign="top" >TBD</td>
3461 <!-- Internals: vertical blanking -->
3463 <sect1 id="drm-vertical-blank">
3464 <title>Vertical Blanking</title>
3466 Vertical blanking plays a major role in graphics rendering. To achieve
3467 tear-free display, users must synchronize page flips and/or rendering to
3468 vertical blanking. The DRM API offers ioctls to perform page flips
3469 synchronized to vertical blanking and wait for vertical blanking.
3472 The DRM core handles most of the vertical blanking management logic, which
3473 involves filtering out spurious interrupts, keeping race-free blanking
3474 counters, coping with counter wrap-around and resets and keeping use
3475 counts. It relies on the driver to generate vertical blanking interrupts
3476 and optionally provide a hardware vertical blanking counter. Drivers must
3477 implement the following operations.
3481 <synopsis>int (*enable_vblank) (struct drm_device *dev, int crtc);
3482 void (*disable_vblank) (struct drm_device *dev, int crtc);</synopsis>
3484 Enable or disable vertical blanking interrupts for the given CRTC.
3488 <synopsis>u32 (*get_vblank_counter) (struct drm_device *dev, int crtc);</synopsis>
3490 Retrieve the value of the vertical blanking counter for the given
3491 CRTC. If the hardware maintains a vertical blanking counter its value
3492 should be returned. Otherwise drivers can use the
3493 <function>drm_vblank_count</function> helper function to handle this
3499 Drivers must initialize the vertical blanking handling core with a call to
3500 <function>drm_vblank_init</function> in their
3501 <methodname>load</methodname> operation. The function will set the struct
3502 <structname>drm_device</structname>
3503 <structfield>vblank_disable_allowed</structfield> field to 0. This will
3504 keep vertical blanking interrupts enabled permanently until the first mode
3505 set operation, where <structfield>vblank_disable_allowed</structfield> is
3506 set to 1. The reason behind this is not clear. Drivers can set the field
3507 to 1 after <function>calling drm_vblank_init</function> to make vertical
3508 blanking interrupts dynamically managed from the beginning.
3511 Vertical blanking interrupts can be enabled by the DRM core or by drivers
3512 themselves (for instance to handle page flipping operations). The DRM core
3513 maintains a vertical blanking use count to ensure that the interrupts are
3514 not disabled while a user still needs them. To increment the use count,
3515 drivers call <function>drm_vblank_get</function>. Upon return vertical
3516 blanking interrupts are guaranteed to be enabled.
3519 To decrement the use count drivers call
3520 <function>drm_vblank_put</function>. Only when the use count drops to zero
3521 will the DRM core disable the vertical blanking interrupts after a delay
3522 by scheduling a timer. The delay is accessible through the vblankoffdelay
3523 module parameter or the <varname>drm_vblank_offdelay</varname> global
3524 variable and expressed in milliseconds. Its default value is 5000 ms.
3525 Zero means never disable, and a negative value means disable immediately.
3526 Drivers may override the behaviour by setting the
3527 <structname>drm_device</structname>
3528 <structfield>vblank_disable_immediate</structfield> flag, which when set
3529 causes vblank interrupts to be disabled immediately regardless of the
3530 drm_vblank_offdelay value. The flag should only be set if there's a
3531 properly working hardware vblank counter present.
3534 When a vertical blanking interrupt occurs drivers only need to call the
3535 <function>drm_handle_vblank</function> function to account for the
3539 Resources allocated by <function>drm_vblank_init</function> must be freed
3540 with a call to <function>drm_vblank_cleanup</function> in the driver
3541 <methodname>unload</methodname> operation handler.
3544 <title>Vertical Blanking and Interrupt Handling Functions Reference</title>
3545 !Edrivers/gpu/drm/drm_irq.c
3546 !Finclude/drm/drmP.h drm_crtc_vblank_waitqueue
3550 <!-- Internals: open/close, file operations and ioctls -->
3553 <title>Open/Close, File Operations and IOCTLs</title>
3555 <title>Open and Close</title>
3556 <synopsis>int (*firstopen) (struct drm_device *);
3557 void (*lastclose) (struct drm_device *);
3558 int (*open) (struct drm_device *, struct drm_file *);
3559 void (*preclose) (struct drm_device *, struct drm_file *);
3560 void (*postclose) (struct drm_device *, struct drm_file *);</synopsis>
3561 <abstract>Open and close handlers. None of those methods are mandatory.
3564 The <methodname>firstopen</methodname> method is called by the DRM core
3565 for legacy UMS (User Mode Setting) drivers only when an application
3566 opens a device that has no other opened file handle. UMS drivers can
3567 implement it to acquire device resources. KMS drivers can't use the
3568 method and must acquire resources in the <methodname>load</methodname>
3572 Similarly the <methodname>lastclose</methodname> method is called when
3573 the last application holding a file handle opened on the device closes
3574 it, for both UMS and KMS drivers. Additionally, the method is also
3575 called at module unload time or, for hot-pluggable devices, when the
3576 device is unplugged. The <methodname>firstopen</methodname> and
3577 <methodname>lastclose</methodname> calls can thus be unbalanced.
3580 The <methodname>open</methodname> method is called every time the device
3581 is opened by an application. Drivers can allocate per-file private data
3582 in this method and store them in the struct
3583 <structname>drm_file</structname> <structfield>driver_priv</structfield>
3584 field. Note that the <methodname>open</methodname> method is called
3585 before <methodname>firstopen</methodname>.
3588 The close operation is split into <methodname>preclose</methodname> and
3589 <methodname>postclose</methodname> methods. Drivers must stop and
3590 cleanup all per-file operations in the <methodname>preclose</methodname>
3591 method. For instance pending vertical blanking and page flip events must
3592 be cancelled. No per-file operation is allowed on the file handle after
3593 returning from the <methodname>preclose</methodname> method.
3596 Finally the <methodname>postclose</methodname> method is called as the
3597 last step of the close operation, right before calling the
3598 <methodname>lastclose</methodname> method if no other open file handle
3599 exists for the device. Drivers that have allocated per-file private data
3600 in the <methodname>open</methodname> method should free it here.
3603 The <methodname>lastclose</methodname> method should restore CRTC and
3604 plane properties to default value, so that a subsequent open of the
3605 device will not inherit state from the previous user. It can also be
3606 used to execute delayed power switching state changes, e.g. in
3607 conjunction with the vga_switcheroo infrastructure (see
3608 <xref linkend="vga_switcheroo"/>). Beyond that KMS drivers should not
3609 do any further cleanup. Only legacy UMS drivers might need to clean up
3610 device state so that the vga console or an independent fbdev driver
3615 <title>File Operations</title>
3616 <synopsis>const struct file_operations *fops</synopsis>
3617 <abstract>File operations for the DRM device node.</abstract>
3619 Drivers must define the file operations structure that forms the DRM
3620 userspace API entry point, even though most of those operations are
3621 implemented in the DRM core. The <methodname>open</methodname>,
3622 <methodname>release</methodname> and <methodname>ioctl</methodname>
3623 operations are handled by
3625 .owner = THIS_MODULE,
3627 .release = drm_release,
3628 .unlocked_ioctl = drm_ioctl,
3629 #ifdef CONFIG_COMPAT
3630 .compat_ioctl = drm_compat_ioctl,
3635 Drivers that implement private ioctls that requires 32/64bit
3636 compatibility support must provide their own
3637 <methodname>compat_ioctl</methodname> handler that processes private
3638 ioctls and calls <function>drm_compat_ioctl</function> for core ioctls.
3641 The <methodname>read</methodname> and <methodname>poll</methodname>
3642 operations provide support for reading DRM events and polling them. They
3647 .llseek = no_llseek,
3651 The memory mapping implementation varies depending on how the driver
3652 manages memory. Pre-GEM drivers will use <function>drm_mmap</function>,
3653 while GEM-aware drivers will use <function>drm_gem_mmap</function>. See
3654 <xref linkend="drm-gem"/>.
3656 .mmap = drm_gem_mmap,
3660 No other file operation is supported by the DRM API.
3664 <title>IOCTLs</title>
3665 <synopsis>struct drm_ioctl_desc *ioctls;
3666 int num_ioctls;</synopsis>
3667 <abstract>Driver-specific ioctls descriptors table.</abstract>
3669 Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls
3670 descriptors table is indexed by the ioctl number offset from the base
3671 value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the
3675 <programlisting>DRM_IOCTL_DEF_DRV(ioctl, func, flags)</programlisting>
3677 <parameter>ioctl</parameter> is the ioctl name. Drivers must define
3678 the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number
3679 offset from DRM_COMMAND_BASE and the ioctl number respectively. The
3680 first macro is private to the device while the second must be exposed
3681 to userspace in a public header.
3684 <parameter>func</parameter> is a pointer to the ioctl handler function
3685 compatible with the <type>drm_ioctl_t</type> type.
3686 <programlisting>typedef int drm_ioctl_t(struct drm_device *dev, void *data,
3687 struct drm_file *file_priv);</programlisting>
3690 <parameter>flags</parameter> is a bitmask combination of the following
3691 values. It restricts how the ioctl is allowed to be called.
3694 DRM_AUTH - Only authenticated callers allowed
3697 DRM_MASTER - The ioctl can only be called on the master file
3701 DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed
3704 DRM_CONTROL_ALLOW - The ioctl can only be called on a control
3708 DRM_UNLOCKED - The ioctl handler will be called without locking
3709 the DRM global mutex. This is the enforced default for kms drivers
3710 (i.e. using the DRIVER_MODESET flag) and hence shouldn't be used
3711 any more for new drivers.
3716 !Edrivers/gpu/drm/drm_ioctl.c
3720 <title>Legacy Support Code</title>
3722 The section very briefly covers some of the old legacy support code which
3723 is only used by old DRM drivers which have done a so-called shadow-attach
3724 to the underlying device instead of registering as a real driver. This
3725 also includes some of the old generic buffer management and command
3726 submission code. Do not use any of this in new and modern drivers.
3730 <title>Legacy Suspend/Resume</title>
3732 The DRM core provides some suspend/resume code, but drivers wanting full
3733 suspend/resume support should provide save() and restore() functions.
3734 These are called at suspend, hibernate, or resume time, and should perform
3735 any state save or restore required by your device across suspend or
3738 <synopsis>int (*suspend) (struct drm_device *, pm_message_t state);
3739 int (*resume) (struct drm_device *);</synopsis>
3741 Those are legacy suspend and resume methods which
3742 <emphasis>only</emphasis> work with the legacy shadow-attach driver
3743 registration functions. New driver should use the power management
3744 interface provided by their bus type (usually through
3745 the struct <structname>device_driver</structname> dev_pm_ops) and set
3746 these methods to NULL.
3751 <title>Legacy DMA Services</title>
3753 This should cover how DMA mapping etc. is supported by the core.
3754 These functions are deprecated and should not be used.
3763 - Document the struct_mutex catch-all lock
3764 - Document connector properties
3766 - Why is the load method optional?
3767 - What are drivers supposed to set the initial display state to, and how?
3768 Connector's DPMS states are not initialized and are thus equal to
3769 DRM_MODE_DPMS_ON. The fbcon compatibility layer calls
3770 drm_helper_disable_unused_functions(), which disables unused encoders and
3771 CRTCs, but doesn't touch the connectors' DPMS state, and
3772 drm_helper_connector_dpms() in reaction to fbdev blanking events. Do drivers
3773 that don't implement (or just don't use) fbcon compatibility need to call
3774 those functions themselves?
3775 - KMS drivers must call drm_vblank_pre_modeset() and drm_vblank_post_modeset()
3776 around mode setting. Should this be done in the DRM core?
3777 - vblank_disable_allowed is set to 1 in the first drm_vblank_post_modeset()
3778 call and never set back to 0. It seems to be safe to permanently set it to 1
3779 in drm_vblank_init() for KMS driver, and it might be safe for UMS drivers as
3780 well. This should be investigated.
3781 - crtc and connector .save and .restore operations are only used internally in
3782 drivers, should they be removed from the core?
3783 - encoder mid-layer .save and .restore operations are only used internally in
3784 drivers, should they be removed from the core?
3785 - encoder mid-layer .detect operation is only used internally in drivers,
3786 should it be removed from the core?
3789 <!-- External interfaces -->
3791 <chapter id="drmExternals">
3792 <title>Userland interfaces</title>
3794 The DRM core exports several interfaces to applications,
3795 generally intended to be used through corresponding libdrm
3796 wrapper functions. In addition, drivers export device-specific
3797 interfaces for use by userspace drivers & device-aware
3798 applications through ioctls and sysfs files.
3801 External interfaces include: memory mapping, context management,
3802 DMA operations, AGP management, vblank control, fence
3803 management, memory management, and output management.
3806 Cover generic ioctls and sysfs layout here. We only need high-level
3807 info, since man pages should cover the rest.
3810 <!-- External: render nodes -->
3813 <title>Render nodes</title>
3815 DRM core provides multiple character-devices for user-space to use.
3816 Depending on which device is opened, user-space can perform a different
3817 set of operations (mainly ioctls). The primary node is always created
3818 and called card<num>. Additionally, a currently
3819 unused control node, called controlD<num> is also
3820 created. The primary node provides all legacy operations and
3821 historically was the only interface used by userspace. With KMS, the
3822 control node was introduced. However, the planned KMS control interface
3823 has never been written and so the control node stays unused to date.
3826 With the increased use of offscreen renderers and GPGPU applications,
3827 clients no longer require running compositors or graphics servers to
3828 make use of a GPU. But the DRM API required unprivileged clients to
3829 authenticate to a DRM-Master prior to getting GPU access. To avoid this
3830 step and to grant clients GPU access without authenticating, render
3831 nodes were introduced. Render nodes solely serve render clients, that
3832 is, no modesetting or privileged ioctls can be issued on render nodes.
3833 Only non-global rendering commands are allowed. If a driver supports
3834 render nodes, it must advertise it via the DRIVER_RENDER
3835 DRM driver capability. If not supported, the primary node must be used
3836 for render clients together with the legacy drmAuth authentication
3840 If a driver advertises render node support, DRM core will create a
3841 separate render node called renderD<num>. There will
3842 be one render node per device. No ioctls except PRIME-related ioctls
3843 will be allowed on this node. Especially GEM_OPEN will be
3844 explicitly prohibited. Render nodes are designed to avoid the
3845 buffer-leaks, which occur if clients guess the flink names or mmap
3846 offsets on the legacy interface. Additionally to this basic interface,
3847 drivers must mark their driver-dependent render-only ioctls as
3848 DRM_RENDER_ALLOW so render clients can use them. Driver
3849 authors must be careful not to allow any privileged ioctls on render
3853 With render nodes, user-space can now control access to the render node
3854 via basic file-system access-modes. A running graphics server which
3855 authenticates clients on the privileged primary/legacy node is no longer
3856 required. Instead, a client can open the render node and is immediately
3857 granted GPU access. Communication between clients (or servers) is done
3858 via PRIME. FLINK from render node to legacy node is not supported. New
3859 clients must not use the insecure FLINK interface.
3862 Besides dropping all modeset/global ioctls, render nodes also drop the
3863 DRM-Master concept. There is no reason to associate render clients with
3864 a DRM-Master as they are independent of any graphics server. Besides,
3865 they must work without any running master, anyway.
3866 Drivers must be able to run without a master object if they support
3867 render nodes. If, on the other hand, a driver requires shared state
3868 between clients which is visible to user-space and accessible beyond
3869 open-file boundaries, they cannot support render nodes.
3873 <!-- External: vblank handling -->
3876 <title>VBlank event handling</title>
3878 The DRM core exposes two vertical blank related ioctls:
3881 <term>DRM_IOCTL_WAIT_VBLANK</term>
3884 This takes a struct drm_wait_vblank structure as its argument,
3885 and it is used to block or request a signal when a specified
3886 vblank event occurs.
3891 <term>DRM_IOCTL_MODESET_CTL</term>
3894 This was only used for user-mode-settind drivers around
3895 modesetting changes to allow the kernel to update the vblank
3896 interrupt after mode setting, since on many devices the vertical
3897 blank counter is reset to 0 at some point during modeset. Modern
3898 drivers should not call this any more since with kernel mode
3899 setting it is a no-op.
3909 <part id="drmDrivers">
3910 <title>DRM Drivers</title>
3914 This second part of the GPU Driver Developer's Guide documents driver
3915 code, implementation details and also all the driver-specific userspace
3916 interfaces. Especially since all hardware-acceleration interfaces to
3917 userspace are driver specific for efficiency and other reasons these
3918 interfaces can be rather substantial. Hence every driver has its own
3923 <chapter id="drmI915">
3924 <title>drm/i915 Intel GFX Driver</title>
3926 The drm/i915 driver supports all (with the exception of some very early
3927 models) integrated GFX chipsets with both Intel display and rendering
3928 blocks. This excludes a set of SoC platforms with an SGX rendering unit,
3929 those have basic support through the gma500 drm driver.
3932 <title>Core Driver Infrastructure</title>
3934 This section covers core driver infrastructure used by both the display
3935 and the GEM parts of the driver.
3938 <title>Runtime Power Management</title>
3939 !Pdrivers/gpu/drm/i915/intel_runtime_pm.c runtime pm
3940 !Idrivers/gpu/drm/i915/intel_runtime_pm.c
3941 !Idrivers/gpu/drm/i915/intel_uncore.c
3944 <title>Interrupt Handling</title>
3945 !Pdrivers/gpu/drm/i915/i915_irq.c interrupt handling
3946 !Fdrivers/gpu/drm/i915/i915_irq.c intel_irq_init intel_irq_init_hw intel_hpd_init
3947 !Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_disable_interrupts
3948 !Fdrivers/gpu/drm/i915/i915_irq.c intel_runtime_pm_enable_interrupts
3951 <title>Intel GVT-g Guest Support(vGPU)</title>
3952 !Pdrivers/gpu/drm/i915/i915_vgpu.c Intel GVT-g guest support
3953 !Idrivers/gpu/drm/i915/i915_vgpu.c
3957 <title>Display Hardware Handling</title>
3959 This section covers everything related to the display hardware including
3960 the mode setting infrastructure, plane, sprite and cursor handling and
3961 display, output probing and related topics.
3964 <title>Mode Setting Infrastructure</title>
3966 The i915 driver is thus far the only DRM driver which doesn't use the
3967 common DRM helper code to implement mode setting sequences. Thus it
3968 has its own tailor-made infrastructure for executing a display
3969 configuration change.
3973 <title>Frontbuffer Tracking</title>
3974 !Pdrivers/gpu/drm/i915/intel_frontbuffer.c frontbuffer tracking
3975 !Idrivers/gpu/drm/i915/intel_frontbuffer.c
3976 !Fdrivers/gpu/drm/i915/i915_gem.c i915_gem_track_fb
3979 <title>Display FIFO Underrun Reporting</title>
3980 !Pdrivers/gpu/drm/i915/intel_fifo_underrun.c fifo underrun handling
3981 !Idrivers/gpu/drm/i915/intel_fifo_underrun.c
3984 <title>Plane Configuration</title>
3986 This section covers plane configuration and composition with the
3987 primary plane, sprites, cursors and overlays. This includes the
3988 infrastructure to do atomic vsync'ed updates of all this state and
3989 also tightly coupled topics like watermark setup and computation,
3990 framebuffer compression and panel self refresh.
3994 <title>Atomic Plane Helpers</title>
3995 !Pdrivers/gpu/drm/i915/intel_atomic_plane.c atomic plane helpers
3996 !Idrivers/gpu/drm/i915/intel_atomic_plane.c
3999 <title>Output Probing</title>
4001 This section covers output probing and related infrastructure like the
4002 hotplug interrupt storm detection and mitigation code. Note that the
4003 i915 driver still uses most of the common DRM helper code for output
4004 probing, so those sections fully apply.
4008 <title>Hotplug</title>
4009 !Pdrivers/gpu/drm/i915/intel_hotplug.c Hotplug
4010 !Idrivers/gpu/drm/i915/intel_hotplug.c
4013 <title>High Definition Audio</title>
4014 !Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port
4015 !Idrivers/gpu/drm/i915/intel_audio.c
4016 !Iinclude/drm/i915_component.h
4019 <title>Panel Self Refresh PSR (PSR/SRD)</title>
4020 !Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD)
4021 !Idrivers/gpu/drm/i915/intel_psr.c
4024 <title>Frame Buffer Compression (FBC)</title>
4025 !Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC)
4026 !Idrivers/gpu/drm/i915/intel_fbc.c
4029 <title>Display Refresh Rate Switching (DRRS)</title>
4030 !Pdrivers/gpu/drm/i915/intel_dp.c Display Refresh Rate Switching (DRRS)
4031 !Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_set_drrs_state
4032 !Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_enable
4033 !Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_disable
4034 !Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_invalidate
4035 !Fdrivers/gpu/drm/i915/intel_dp.c intel_edp_drrs_flush
4036 !Fdrivers/gpu/drm/i915/intel_dp.c intel_dp_drrs_init
4041 !Pdrivers/gpu/drm/i915/i915_reg.h DPIO
4043 <title>Dual channel PHY (VLV/CHV/BXT)</title>
4045 <colspec colname="c0" />
4046 <colspec colname="c1" />
4047 <colspec colname="c2" />
4048 <colspec colname="c3" />
4049 <colspec colname="c4" />
4050 <colspec colname="c5" />
4051 <colspec colname="c6" />
4052 <colspec colname="c7" />
4053 <spanspec spanname="ch0" namest="c0" nameend="c3" />
4054 <spanspec spanname="ch1" namest="c4" nameend="c7" />
4055 <spanspec spanname="ch0pcs01" namest="c0" nameend="c1" />
4056 <spanspec spanname="ch0pcs23" namest="c2" nameend="c3" />
4057 <spanspec spanname="ch1pcs01" namest="c4" nameend="c5" />
4058 <spanspec spanname="ch1pcs23" namest="c6" nameend="c7" />
4061 <entry spanname="ch0">CH0</entry>
4062 <entry spanname="ch1">CH1</entry>
4065 <tbody valign="top" align="center">
4067 <entry spanname="ch0">CMN/PLL/REF</entry>
4068 <entry spanname="ch1">CMN/PLL/REF</entry>
4071 <entry spanname="ch0pcs01">PCS01</entry>
4072 <entry spanname="ch0pcs23">PCS23</entry>
4073 <entry spanname="ch1pcs01">PCS01</entry>
4074 <entry spanname="ch1pcs23">PCS23</entry>
4087 <entry spanname="ch0">DDI0</entry>
4088 <entry spanname="ch1">DDI1</entry>
4094 <title>Single channel PHY (CHV/BXT)</title>
4096 <colspec colname="c0" />
4097 <colspec colname="c1" />
4098 <colspec colname="c2" />
4099 <colspec colname="c3" />
4100 <spanspec spanname="ch0" namest="c0" nameend="c3" />
4101 <spanspec spanname="ch0pcs01" namest="c0" nameend="c1" />
4102 <spanspec spanname="ch0pcs23" namest="c2" nameend="c3" />
4105 <entry spanname="ch0">CH0</entry>
4108 <tbody valign="top" align="center">
4110 <entry spanname="ch0">CMN/PLL/REF</entry>
4113 <entry spanname="ch0pcs01">PCS01</entry>
4114 <entry spanname="ch0pcs23">PCS23</entry>
4123 <entry spanname="ch0">DDI2</entry>
4131 <title>CSR firmware support for DMC</title>
4132 !Pdrivers/gpu/drm/i915/intel_csr.c csr support for dmc
4133 !Idrivers/gpu/drm/i915/intel_csr.c
4138 <title>Memory Management and Command Submission</title>
4140 This sections covers all things related to the GEM implementation in the
4144 <title>Batchbuffer Parsing</title>
4145 !Pdrivers/gpu/drm/i915/i915_cmd_parser.c batch buffer command parser
4146 !Idrivers/gpu/drm/i915/i915_cmd_parser.c
4149 <title>Batchbuffer Pools</title>
4150 !Pdrivers/gpu/drm/i915/i915_gem_batch_pool.c batch pool
4151 !Idrivers/gpu/drm/i915/i915_gem_batch_pool.c
4154 <title>Logical Rings, Logical Ring Contexts and Execlists</title>
4155 !Pdrivers/gpu/drm/i915/intel_lrc.c Logical Rings, Logical Ring Contexts and Execlists
4156 !Idrivers/gpu/drm/i915/intel_lrc.c
4159 <title>Global GTT views</title>
4160 !Pdrivers/gpu/drm/i915/i915_gem_gtt.c Global GTT views
4161 !Idrivers/gpu/drm/i915/i915_gem_gtt.c
4164 <title>GTT Fences and Swizzling</title>
4165 !Idrivers/gpu/drm/i915/i915_gem_fence.c
4167 <title>Global GTT Fence Handling</title>
4168 !Pdrivers/gpu/drm/i915/i915_gem_fence.c fence register handling
4171 <title>Hardware Tiling and Swizzling Details</title>
4172 !Pdrivers/gpu/drm/i915/i915_gem_fence.c tiling swizzling details
4176 <title>Object Tiling IOCTLs</title>
4177 !Idrivers/gpu/drm/i915/i915_gem_tiling.c
4178 !Pdrivers/gpu/drm/i915/i915_gem_tiling.c buffer object tiling
4181 <title>Buffer Object Eviction</title>
4183 This section documents the interface functions for evicting buffer
4184 objects to make space available in the virtual gpu address spaces.
4185 Note that this is mostly orthogonal to shrinking buffer objects
4186 caches, which has the goal to make main memory (shared with the gpu
4187 through the unified memory architecture) available.
4189 !Idrivers/gpu/drm/i915/i915_gem_evict.c
4192 <title>Buffer Object Memory Shrinking</title>
4194 This section documents the interface function for shrinking memory
4195 usage of buffer object caches. Shrinking is used to make main memory
4196 available. Note that this is mostly orthogonal to evicting buffer
4197 objects, which has the goal to make space in gpu virtual address
4200 !Idrivers/gpu/drm/i915/i915_gem_shrinker.c
4204 <title>GuC-based Command Submission</title>
4207 !Pdrivers/gpu/drm/i915/intel_guc_loader.c GuC-specific firmware loader
4208 !Idrivers/gpu/drm/i915/intel_guc_loader.c
4211 <title>GuC Client</title>
4212 !Pdrivers/gpu/drm/i915/i915_guc_submission.c GuC-based command submissison
4213 !Idrivers/gpu/drm/i915/i915_guc_submission.c
4218 <title> Tracing </title>
4220 This sections covers all things related to the tracepoints implemented in
4224 <title> i915_ppgtt_create and i915_ppgtt_release </title>
4225 !Pdrivers/gpu/drm/i915/i915_trace.h i915_ppgtt_create and i915_ppgtt_release tracepoints
4228 <title> i915_context_create and i915_context_free </title>
4229 !Pdrivers/gpu/drm/i915/i915_trace.h i915_context_create and i915_context_free tracepoints
4232 <title> switch_mm </title>
4233 !Pdrivers/gpu/drm/i915/i915_trace.h switch_mm tracepoint
4238 !Cdrivers/gpu/drm/i915/i915_irq.c
4241 <part id="vga_switcheroo">
4242 <title>vga_switcheroo</title>
4244 !Pdrivers/gpu/vga/vga_switcheroo.c Overview
4247 <chapter id="modes_of_use">
4248 <title>Modes of Use</title>
4250 <title>Manual switching and manual power control</title>
4251 !Pdrivers/gpu/vga/vga_switcheroo.c Manual switching and manual power control
4254 <title>Driver power control</title>
4255 !Pdrivers/gpu/vga/vga_switcheroo.c Driver power control
4259 <chapter id="pubfunctions">
4260 <title>Public functions</title>
4261 !Edrivers/gpu/vga/vga_switcheroo.c
4264 <chapter id="pubstructures">
4265 <title>Public structures</title>
4266 !Finclude/linux/vga_switcheroo.h vga_switcheroo_handler
4267 !Finclude/linux/vga_switcheroo.h vga_switcheroo_client_ops
4270 <chapter id="pubconstants">
4271 <title>Public constants</title>
4272 !Finclude/linux/vga_switcheroo.h vga_switcheroo_client_id
4273 !Finclude/linux/vga_switcheroo.h vga_switcheroo_state
4276 <chapter id="privstructures">
4277 <title>Private structures</title>
4278 !Fdrivers/gpu/vga/vga_switcheroo.c vgasr_priv
4279 !Fdrivers/gpu/vga/vga_switcheroo.c vga_switcheroo_client
4282 !Cdrivers/gpu/vga/vga_switcheroo.c
4283 !Cinclude/linux/vga_switcheroo.h
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