Commit 9d0a79e5 authored by Sakari Ailus's avatar Sakari Ailus Committed by Mauro Carvalho Chehab
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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 Original line 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

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

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

access the device.

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.