Add documentation for each of the controls
V4L2_CID_NOTIFY_GAIN_RED
V4L2_CID_NOTIFY_GAIN_GREENR
V4L2_CID_NOTIFY_GAIN_BLUE
V4L2_CID_NOTIFY_GAIN_GREENB
These controls are required by sensors that need to know what colour
gains will be applied to pixels by downstream processing (such as by
an ISP), though the sensor does not apply these gains itself.
Signed-off-by: David Plowman <david.plowman@xxxxxxxxxxxxxxx>
---
.../media/v4l/ext-ctrls-image-source.rst | 25 +++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-source.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-source.rst
index de43f5c8486d..d50b56156a8e 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-source.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-source.rst
@@ -72,3 +72,28 @@ Image Source Control IDs
* - __u32
- ``height``
- Height of the area.
+
+``V4L2_CID_NOTIFY_GAIN_RED (integer)``
+ Please refer to ``V4L2_CID_NOTIFY_GAIN_GREENB`` below.
+
+``V4L2_CID_NOTIFY_GAIN_GREENR (integer)``
+ Please refer to ``V4L2_CID_NOTIFY_GAIN_GREENB`` below.
+
+``V4L2_CID_NOTIFY_GAIN_BLUE (integer)``
+ Please refer to ``V4L2_CID_NOTIFY_GAIN_GREENB`` below.
+
+``V4L2_CID_NOTIFY_GAIN_GREENB (integer)``
+ Note: this description covers all four ``V4L2_CID_NOTIFY_GAIN``
+ controls, according to the Bayer channel indicated at the end of
+ the control name.
+
+ The sensor is notified what gain will be applied to this Bayer
+ channel by subsequent processing (such as by an ISP). The sensor
+ is merely informed of this value in case it performs processing
+ that requires it, but it does not apply it to the output pixels
+ themselves.
+
+ The units for the gain value are linear, with the default value
+ being shared between all four controls and representing a gain of
+ exactly 1. Other control properties, such as ranges, should also
+ be common.
--
2.17.1
