Hi Jacopo, On Tue, Jul 04, 2023 at 04:05:44PM +0200, Jacopo Mondi wrote: > 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 :) Sorry, I'm referring to your comment: "I think this might be useful yes. A few paragraph above the frame duration calculation formula is expressed as well, so I guess adding one for this is helpful too" > > > > > 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. Ok. Thanks, need to find some docs regarding this units :'( For this I think having some good reference/formula here would help users to find the corrispective value into the sensor datasheet. I just proved this to you :) Regards, Tommaso > > > 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 > > >
