Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) .. SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) The cafe_ccic driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) ====================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) Author: Jonathan Corbet <corbet@lwn.net>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) Introduction
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) ------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) "cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) controller.  This is the controller found in first-generation OLPC systems,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) and this driver was written with support from the OLPC project.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) Current status: the core driver works.  It can generate data in YUV422,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) RGB565, and RGB444 formats.  (Anybody looking at the code will see RGB32 as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) well, but that is a debugging aid which will be removed shortly).  VGA and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) QVGA modes work; CIF is there but the colors remain funky.  Only the OV7670
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) sensor is known to work with this controller at this time.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) To try it out: either of these commands will work:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) .. code-block:: none
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)      $ mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)      $ mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) The "xawtv" utility also works; gqcam does not, for unknown reasons.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) Load time options
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) -----------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) There are a few load-time options, most of which can be changed after
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) loading via sysfs as well:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36)  - alloc_bufs_at_load:  Normally, the driver will not allocate any DMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37)    buffers until the time comes to transfer data.  If this option is set,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)    then worst-case-sized buffers will be allocated at module load time.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39)    This option nails down the memory for the life of the module, but
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)    perhaps decreases the chances of an allocation failure later on.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42)  - dma_buf_size: The size of DMA buffers to allocate.  Note that this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)    option is only consulted for load-time allocation; when buffers are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)    allocated at run time, they will be sized appropriately for the current
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45)    camera settings.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47)  - n_dma_bufs: The controller can cycle through either two or three DMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48)    buffers.  Normally, the driver tries to use three buffers; on faster
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)    systems, however, it will work well with only two.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)  - min_buffers: The minimum number of streaming I/O buffers that the driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)    will consent to work with.  Default is one, but, on slower systems,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)    better behavior with mplayer can be achieved by setting to a higher
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54)    value (like six).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56)  - max_buffers: The maximum number of streaming I/O buffers; default is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)    ten.  That number was carefully picked out of a hat and should not be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58)    assumed to actually mean much of anything.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60)  - flip: If this boolean parameter is set, the sensor will be instructed to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61)    invert the video image.  Whether it makes sense is determined by how
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62)    your particular camera is mounted.