Add documentation for the V4L2_CID_NOTIFY_GAINS control.
This control is 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 | 15 +++++++++++++++
1 file changed, 15 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..c1793fda1429 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 +72,18 @@ Image Source Control IDs
* - __u32
- ``height``
- Height of the area.
+
+``V4L2_CID_NOTIFY_GAINS (integer)``
+ The sensor is notified what gains will be applied to the different
+ colour channels by subsequent processing (such as by an ISP). The
+ sensor is merely informed of these values in case it performs
+ processing that requires them, but it does not apply them itself to
+ the output pixels.
+
+ For Bayer sensors this is an array control taking 4 gain values,
+ being the gains for each of the Bayer channels. The gains are always
+ in the order B, Gb, Gr and R, irrespective of the exact Bayer order
+ of the sensor itself.
+
+ The units for the gain values are linear, with the default value
+ representing a gain of exactly 1.
--
2.30.2
