include/drm/drm_modeset_lock.h

   1 /*
   2  * Copyright (C) 2014 Red Hat
   3  * Author: Rob Clark <robdclark@gmail.com>
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  19  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  20  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  21  * OTHER DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #ifndef DRM_MODESET_LOCK_H_
  25 #define DRM_MODESET_LOCK_H_
  26
  27 #include <linux/ww_mutex.h>
  28
  29 struct drm_modeset_lock;
  30
  31 /**
  32  * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)
  33  * @ww_ctx: base acquire ctx
  34  * @contended: used internally for -EDEADLK handling
  35  * @locked: list of held locks
  36  *
  37  * Each thread competing for a set of locks must use one acquire
  38  * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
  39  * retry.
  40  */
  41 struct drm_modeset_acquire_ctx {
  42
  43         struct ww_acquire_ctx ww_ctx;
  44
  45         /**
  46          * Contended lock: if a lock is contended you should only call
  47          * drm_modeset_backoff() which drops locks and slow-locks the
  48          * contended lock.
  49          */
  50         struct drm_modeset_lock *contended;
  51
  52         /**
  53          * list of held locks (drm_modeset_lock)
  54          */
  55         struct list_head locked;
  56
  57         /**
  58          * Trylock mode, use only for panic handlers!
  59          */
  60         bool trylock_only;
  61 };
  62
  63 /**
  64  * struct drm_modeset_lock - used for locking modeset resources.
  65  * @mutex: resource locking
  66  * @head: used to hold it's place on state->locked list when
  67  *    part of an atomic update
  68  *
  69  * Used for locking CRTCs and other modeset resources.
  70  */
  71 struct drm_modeset_lock {
  72         /**
  73          * modeset lock
  74          */
  75         struct ww_mutex mutex;
  76
  77         /**
  78          * Resources that are locked as part of an atomic update are added
  79          * to a list (so we know what to unlock at the end).
  80          */
  81         struct list_head head;
  82 };
  83
  84 extern struct ww_class crtc_ww_class;
  85
  86 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
  87                 uint32_t flags);
  88 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
  89 void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
  90 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
  91 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
  92
  93 /**
  94  * drm_modeset_lock_init - initialize lock
  95  * @lock: lock to init
  96  */
  97 static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
  98 {
  99         ww_mutex_init(&lock->mutex, &crtc_ww_class);
 100         INIT_LIST_HEAD(&lock->head);
 101 }
 102
 103 /**
 104  * drm_modeset_lock_fini - cleanup lock
 105  * @lock: lock to cleanup
 106  */
 107 static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
 108 {
 109         WARN_ON(!list_empty(&lock->head));
 110 }
 111
 112 /**
 113  * drm_modeset_is_locked - equivalent to mutex_is_locked()
 114  * @lock: lock to check
 115  */
 116 static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
 117 {
 118         return ww_mutex_is_locked(&lock->mutex);
 119 }
 120
 121 int drm_modeset_lock(struct drm_modeset_lock *lock,
 122                 struct drm_modeset_acquire_ctx *ctx);
 123 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
 124                 struct drm_modeset_acquire_ctx *ctx);
 125 void drm_modeset_unlock(struct drm_modeset_lock *lock);
 126
 127 struct drm_device;
 128 struct drm_crtc;
 129
 130 void drm_modeset_lock_all(struct drm_device *dev);
 131 int __drm_modeset_lock_all(struct drm_device *dev, bool trylock);
 132 void drm_modeset_unlock_all(struct drm_device *dev);
 133 void drm_modeset_lock_crtc(struct drm_crtc *crtc);
 134 void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
 135 void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
 136 struct drm_modeset_acquire_ctx *
 137 drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
 138
 139 int drm_modeset_lock_all_crtcs(struct drm_device *dev,
 140                 struct drm_modeset_acquire_ctx *ctx);
 141
 142 #endif /* DRM_MODESET_LOCK_H_ */