linux/Documentation/video4linux/cafe_ccic
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   1"cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera
   2controller.  This is the controller found in first-generation OLPC systems,
   3and this driver was written with support from the OLPC project.
   4
   5Current status: the core driver works.  It can generate data in YUV422,
   6RGB565, and RGB444 formats.  (Anybody looking at the code will see RGB32 as
   7well, but that is a debugging aid which will be removed shortly).  VGA and
   8QVGA modes work; CIF is there but the colors remain funky.  Only the OV7670
   9sensor is known to work with this controller at this time.
  10
  11To try it out: either of these commands will work:
  12
  13     mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound
  14     mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound
  15
  16The "xawtv" utility also works; gqcam does not, for unknown reasons.
  17
  18There are a few load-time options, most of which can be changed after
  19loading via sysfs as well:
  20
  21 - alloc_bufs_at_load:  Normally, the driver will not allocate any DMA
  22   buffers until the time comes to transfer data.  If this option is set,
  23   then worst-case-sized buffers will be allocated at module load time.
  24   This option nails down the memory for the life of the module, but
  25   perhaps decreases the chances of an allocation failure later on.
  26
  27 - dma_buf_size: The size of DMA buffers to allocate.  Note that this
  28   option is only consulted for load-time allocation; when buffers are
  29   allocated at run time, they will be sized appropriately for the current
  30   camera settings.
  31
  32 - n_dma_bufs: The controller can cycle through either two or three DMA
  33   buffers.  Normally, the driver tries to use three buffers; on faster
  34   systems, however, it will work well with only two.
  35
  36 - min_buffers: The minimum number of streaming I/O buffers that the driver
  37   will consent to work with.  Default is one, but, on slower systems,
  38   better behavior with mplayer can be achieved by setting to a higher
  39   value (like six).
  40
  41 - max_buffers: The maximum number of streaming I/O buffers; default is
  42   ten.  That number was carefully picked out of a hat and should not be
  43   assumed to actually mean much of anything.
  44
  45 - flip: If this boolean parameter is set, the sensor will be instructed to
  46   invert the video image.  Whether it makes sense is determined by how
  47   your particular camera is mounted.
  48
  49Work is ongoing with this driver, stay tuned.
  50
  51jon
  52
  53Jonathan Corbet
  54corbet@lwn.net
  55
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