162306a36Sopenharmony_ci.. SPDX-License-Identifier: GPL-2.0 262306a36Sopenharmony_ci 362306a36Sopenharmony_ciThe cafe_ccic driver 462306a36Sopenharmony_ci==================== 562306a36Sopenharmony_ci 662306a36Sopenharmony_ciAuthor: Jonathan Corbet <corbet@lwn.net> 762306a36Sopenharmony_ci 862306a36Sopenharmony_ciIntroduction 962306a36Sopenharmony_ci------------ 1062306a36Sopenharmony_ci 1162306a36Sopenharmony_ci"cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera 1262306a36Sopenharmony_cicontroller. This is the controller found in first-generation OLPC systems, 1362306a36Sopenharmony_ciand this driver was written with support from the OLPC project. 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ciCurrent status: the core driver works. It can generate data in YUV422, 1662306a36Sopenharmony_ciRGB565, and RGB444 formats. (Anybody looking at the code will see RGB32 as 1762306a36Sopenharmony_ciwell, but that is a debugging aid which will be removed shortly). VGA and 1862306a36Sopenharmony_ciQVGA modes work; CIF is there but the colors remain funky. Only the OV7670 1962306a36Sopenharmony_cisensor is known to work with this controller at this time. 2062306a36Sopenharmony_ci 2162306a36Sopenharmony_ciTo try it out: either of these commands will work: 2262306a36Sopenharmony_ci 2362306a36Sopenharmony_ci.. code-block:: none 2462306a36Sopenharmony_ci 2562306a36Sopenharmony_ci $ mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound 2662306a36Sopenharmony_ci $ mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound 2762306a36Sopenharmony_ci 2862306a36Sopenharmony_ciThe "xawtv" utility also works; gqcam does not, for unknown reasons. 2962306a36Sopenharmony_ci 3062306a36Sopenharmony_ciLoad time options 3162306a36Sopenharmony_ci----------------- 3262306a36Sopenharmony_ci 3362306a36Sopenharmony_ciThere are a few load-time options, most of which can be changed after 3462306a36Sopenharmony_ciloading via sysfs as well: 3562306a36Sopenharmony_ci 3662306a36Sopenharmony_ci - alloc_bufs_at_load: Normally, the driver will not allocate any DMA 3762306a36Sopenharmony_ci buffers until the time comes to transfer data. If this option is set, 3862306a36Sopenharmony_ci then worst-case-sized buffers will be allocated at module load time. 3962306a36Sopenharmony_ci This option nails down the memory for the life of the module, but 4062306a36Sopenharmony_ci perhaps decreases the chances of an allocation failure later on. 4162306a36Sopenharmony_ci 4262306a36Sopenharmony_ci - dma_buf_size: The size of DMA buffers to allocate. Note that this 4362306a36Sopenharmony_ci option is only consulted for load-time allocation; when buffers are 4462306a36Sopenharmony_ci allocated at run time, they will be sized appropriately for the current 4562306a36Sopenharmony_ci camera settings. 4662306a36Sopenharmony_ci 4762306a36Sopenharmony_ci - n_dma_bufs: The controller can cycle through either two or three DMA 4862306a36Sopenharmony_ci buffers. Normally, the driver tries to use three buffers; on faster 4962306a36Sopenharmony_ci systems, however, it will work well with only two. 5062306a36Sopenharmony_ci 5162306a36Sopenharmony_ci - min_buffers: The minimum number of streaming I/O buffers that the driver 5262306a36Sopenharmony_ci will consent to work with. Default is one, but, on slower systems, 5362306a36Sopenharmony_ci better behavior with mplayer can be achieved by setting to a higher 5462306a36Sopenharmony_ci value (like six). 5562306a36Sopenharmony_ci 5662306a36Sopenharmony_ci - max_buffers: The maximum number of streaming I/O buffers; default is 5762306a36Sopenharmony_ci ten. That number was carefully picked out of a hat and should not be 5862306a36Sopenharmony_ci assumed to actually mean much of anything. 5962306a36Sopenharmony_ci 6062306a36Sopenharmony_ci - flip: If this boolean parameter is set, the sensor will be instructed to 6162306a36Sopenharmony_ci invert the video image. Whether it makes sense is determined by how 6262306a36Sopenharmony_ci your particular camera is mounted. 63