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1.. SPDX-License-Identifier: GPL-2.02 3The cafe_ccic driver4====================5 6Author: Jonathan Corbet <corbet@lwn.net>7 8Introduction9------------10 11"cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera12controller. This is the controller found in first-generation OLPC systems,13and this driver was written with support from the OLPC project.14 15Current status: the core driver works. It can generate data in YUV422,16RGB565, and RGB444 formats. (Anybody looking at the code will see RGB32 as17well, but that is a debugging aid which will be removed shortly). VGA and18QVGA modes work; CIF is there but the colors remain funky. Only the OV767019sensor is known to work with this controller at this time.20 21To try it out: either of these commands will work:22 23.. code-block:: none24 25 $ mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound26 $ mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound27 28The "xawtv" utility also works; gqcam does not, for unknown reasons.29 30Load time options31-----------------32 33There are a few load-time options, most of which can be changed after34loading via sysfs as well:35 36 - alloc_bufs_at_load: Normally, the driver will not allocate any DMA37 buffers until the time comes to transfer data. If this option is set,38 then worst-case-sized buffers will be allocated at module load time.39 This option nails down the memory for the life of the module, but40 perhaps decreases the chances of an allocation failure later on.41 42 - dma_buf_size: The size of DMA buffers to allocate. Note that this43 option is only consulted for load-time allocation; when buffers are44 allocated at run time, they will be sized appropriately for the current45 camera settings.46 47 - n_dma_bufs: The controller can cycle through either two or three DMA48 buffers. Normally, the driver tries to use three buffers; on faster49 systems, however, it will work well with only two.50 51 - min_buffers: The minimum number of streaming I/O buffers that the driver52 will consent to work with. Default is one, but, on slower systems,53 better behavior with mplayer can be achieved by setting to a higher54 value (like six).55 56 - max_buffers: The maximum number of streaming I/O buffers; default is57 ten. That number was carefully picked out of a hat and should not be58 assumed to actually mean much of anything.59 60 - flip: If this boolean parameter is set, the sensor will be instructed to61 invert the video image. Whether it makes sense is determined by how62 your particular camera is mounted.63