Hi Tommaso On Tue, Jul 04, 2023 at 03:51:43PM +0200, Tommaso Merciai wrote: > 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. I might have missed what other comment you are referring to :) > > Can you add formula/references about this point I think you are referring on "tline" units (maybe I'm completely wrong :) ), Is "tline" the line duration ? If that's the case then no, I am referring to the number of lines, not their duration. > 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 > >
