Documentation/media/v4l-drivers/davinci-vpbe.rst

   1 The VPBE V4L2 driver design
   2 ===========================
   3
   4 File partitioning
   5 -----------------
   6
   7  V4L2 display device driver
   8          drivers/media/platform/davinci/vpbe_display.c
   9          drivers/media/platform/davinci/vpbe_display.h
  10
  11  VPBE display controller
  12          drivers/media/platform/davinci/vpbe.c
  13          drivers/media/platform/davinci/vpbe.h
  14
  15  VPBE venc sub device driver
  16          drivers/media/platform/davinci/vpbe_venc.c
  17          drivers/media/platform/davinci/vpbe_venc.h
  18          drivers/media/platform/davinci/vpbe_venc_regs.h
  19
  20  VPBE osd driver
  21          drivers/media/platform/davinci/vpbe_osd.c
  22          drivers/media/platform/davinci/vpbe_osd.h
  23          drivers/media/platform/davinci/vpbe_osd_regs.h
  24
  25 Functional partitioning
  26 -----------------------
  27
  28 Consists of the following (in the same order as the list under file
  29 partitioning):
  30
  31  1. V4L2 display driver
  32     Implements creation of video2 and video3 device nodes and
  33     provides v4l2 device interface to manage VID0 and VID1 layers.
  34
  35  2. Display controller
  36     Loads up VENC, OSD and external encoders such as ths8200. It provides
  37     a set of API calls to V4L2 drivers to set the output/standards
  38     in the VENC or external sub devices. It also provides
  39     a device object to access the services from OSD subdevice
  40     using sub device ops. The connection of external encoders to VENC LCD
  41     controller port is done at init time based on default output and standard
  42     selection or at run time when application change the output through
  43     V4L2 IOCTLs.
  44
  45     When connected to an external encoder, vpbe controller is also responsible
  46     for setting up the interface between VENC and external encoders based on
  47     board specific settings (specified in board-xxx-evm.c). This allows
  48     interfacing external encoders such as ths8200. The setup_if_config()
  49     is implemented for this as well as configure_venc() (part of the next patch)
  50     API to set timings in VENC for a specific display resolution. As of this
  51     patch series, the interconnection and enabling and setting of the external
  52     encoders is not present, and would be a part of the next patch series.
  53
  54  3. VENC subdevice module
  55     Responsible for setting outputs provided through internal DACs and also
  56     setting timings at LCD controller port when external encoders are connected
  57     at the port or LCD panel timings required. When external encoder/LCD panel
  58     is connected, the timings for a specific standard/preset is retrieved from
  59     the board specific table and the values are used to set the timings in
  60     venc using non-standard timing mode.
  61
  62     Support LCD Panel displays using the VENC. For example to support a Logic
  63     PD display, it requires setting up the LCD controller port with a set of
  64     timings for the resolution supported and setting the dot clock. So we could
  65     add the available outputs as a board specific entry (i.e add the "LogicPD"
  66     output name to board-xxx-evm.c). A table of timings for various LCDs
  67     supported can be maintained in the board specific setup file to support
  68     various LCD displays.As of this patch a basic driver is present, and this
  69     support for external encoders and displays forms a part of the next
  70     patch series.
  71
  72  4. OSD module
  73     OSD module implements all OSD layer management and hardware specific
  74     features. The VPBE module interacts with the OSD for enabling and
  75     disabling appropriate features of the OSD.
  76
  77 Current status
  78 --------------
  79
  80 A fully functional working version of the V4L2 driver is available. This
  81 driver has been tested with NTSC and PAL standards and buffer streaming.
  82
  83 To be done
  84 ----------
  85
  86 vpbe display controller
  87     - Add support for external encoders.
  88     - add support for selecting external encoder as default at probe time.
  89
  90 vpbe venc sub device
  91     - add timings for supporting ths8200
  92     - add support for LogicPD LCD.
  93
  94 FB drivers
  95     - Add support for fbdev drivers.- Ready and part of subsequent patches.