Commit 9d0a79e5 authored by Sakari Ailus's avatar Sakari Ailus Committed by Mauro Carvalho Chehab
Browse files

media: Documentation: v4l: Document required controls on camera sensors 



Raw camera sensors connected to parallel or CSI-2 busses need to implement
V4L2_CID_LINK_FREQ control so receiver drivers can configure the hardware
accordingly.

Document this. Also say V4L2_CID_PIXEL_RATE is recommended for such
hardware.

Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent d3ed195b

Documentation/driver-api/media/camera-sensor.rst

+13 −0
Original line number Diff line number Diff line
@@ -132,3 +132,16 @@ used to obtain device's power state after the power state transition: 
The function returns a non-zero value if it succeeded getting the power count or

runtime PM was disabled, in either of which cases the driver may proceed to

access the device.



Controls

--------



For camera sensors that are connected to a bus where transmitter and receiver

require common configuration set by drivers, such as CSI-2 or parallel (BT.601

or BT.656) bus, the ``V4L2_CID_LINK_FREQ`` control is mandatory on transmitter

drivers. Receiver drivers can use the ``V4L2_CID_LINK_FREQ`` to query the

frequency used on the bus.



The transmitter drivers should also implement ``V4L2_CID_PIXEL_RATE`` control in

order to tell the maximum pixel rate to the receiver. This is required on raw

camera sensors.