Hi Jacopo, On Mon, Jul 03, 2023 at 10:29:10PM +0200, Jacopo Mondi wrote: > Document the suggested way to exposure controls for exposure and gain > for camera sensor drivers. > > Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> > --- > .../driver-api/media/camera-sensor.rst | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst > index ee4a7fe5f72a..dfe8f35aecea 100644 > --- a/Documentation/driver-api/media/camera-sensor.rst > +++ b/Documentation/driver-api/media/camera-sensor.rst > @@ -189,3 +189,22 @@ the ``V4L2_CID_VFLIP`` and ``V4L2_CID_HFLIP`` controls with the > a flip can potentially change the output buffer content layout. Flips should > also be taken into account when enumerating and handling media bus formats > on the camera sensor source pads. > + > +Exposure and Gain Control > +------------------------- > + > +Camera sensor drivers that allows applications to control the image exposure > +and gain should do so by exposing dedicated controls to applications. > + > +Exposure time is controlled by registering the ``V4L2_CID_EXPOSURE`` control. > +The control definition does not specify a unit to allow maximum flexibility > +for multiple device types, but when used for camera sensor driver it should be > +expressed in unit of lines whenever possible. Same comment here. Can you add formula/references about this point I think you are referring on "tline" units (maybe I'm completely wrong :) ), but to be honest checking also the some sensors datasheet I don't find to much infos about this units. Would be really helpfull to add some details on this point. > + > +Camera sensor driver should try whenever possible to distinguish between the > +analogue and digital gain control functions. Analogue gain is a multiplier > +factor applied to all color channels on the pixel array before they get > +converted in the digital domain. It should be be made controllable by > +registering the ``V4L2_CID_ANALOGUE_GAIN`` control, expressed as a device > +specific gain code. Digital gain control is optional and should be exposed to > +applications by registering ``V4L2_CID_DIGITAL_GAIN``. Camera sensor drivers are > -- This part looks good to me. Thanks, Tommaso > 2.40.1 >
