Re: [PATCH 2/2] media: v4l2-ctrls: Document V4L2_CID_NOTIFY_GAIN_XXX controls

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Added Laurent to cc.

On Wed, May 19, 2021 at 10:01:21PM +0300, Sakari Ailus wrote:
> Hi David,
> 
> Thanks for the patch.
> 
> Cc'ing Laurent, too.
> 
> On Mon, May 17, 2021 at 11:02:40AM +0100, David Plowman wrote:
> > 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      | 28 +++++++++++++++++++
> >  1 file changed, 28 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..f824d6c36ae8 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 +72,31 @@ Image Source Control IDs
> >      * - __u32
> >        - ``height``
> >        - Height of the area.
> > +
> > +``V4L2_CID_NOTIFY_GAIN_RED (integer)``
> > +    Notify the sensor what gain will be applied to red pixels by the
> > +    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 is not applied to the output pixels themselves. The
> > +    units are determined by the sensor driver.
> 
> I wonder if this should say the default value should reflect gain of 1. It
> probably wouldn't hurt at least.
> 
> > +
> > +``V4L2_CID_NOTIFY_GAIN_GREENR (integer)``
> > +    Notify the sensor what gain will be applied to green pixels (on
> > +    red rows) 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 is not applied to the output pixels
> > +    themselves. The units are determined by the sensor driver.
> > +
> > +``V4L2_CID_NOTIFY_GAIN_BLUE (integer)``
> > +    Notify the sensor what gain will be applied to blue pixels by the
> > +    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 is not applied to the output pixels themselves. The
> > +    units are determined by the sensor driver.
> > +
> > +``V4L2_CID_NOTIFY_GAIN_GREENB (integer)``
> > +    Notify the sensor what gain will be applied to green pixels (on
> > +    blue rows) 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 is not applied to the output pixels
> > +    themselves. The units are determined by the sensor driver.
> 
> -- 
> Kind regards,
> 
> Sakari Ailus

-- 
Sakari Ailus



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