Hi David, Thank you for the patch. On Tue, Aug 10, 2021 at 10:38:11AM +0100, David Plowman wrote: > 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 | 20 +++++++++++++++++++ > 1 file changed, 20 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..ba83cc0867d2 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 +72,23 @@ Image Source Control IDs > * - __u32 > - ``height`` > - Height of the area. > + > +``V4L2_CID_NOTIFY_GAINS (integer array)`` > + 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. > + > + The use of an array allows this control to be extended to sensors > + with, for example, non-Bayer CFAs (colour filter arrays). > + > + Currently it is defined only for Bayer sensors, and 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. I'd swap the above two paragraphs. > + > + The units for the gain values are linear, with the default value > + representing a gain of exactly 1. For example, if this default value > + is reported as being (say) 128, then a value of 256 would represent > + a gain of exactly 2. Maybe 1.0 and 2.0 instead of 1 and 2 to show that the gains values themselves can be fractional ? With those two minor issues addressed if deemed to be worth it, Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> -- Regards, Laurent Pinchart
