Hi Jacopo Thanks for adding documentation. Sorry I couldn't be at your presentation, but I'll find the slides (and recording if there is one). On Mon, 3 Jul 2023 at 21:29, Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> wrote: > > Document the requirement of notifying to userspace the possible > re-ordering of the color sample components when a vertical or horizontal > flip is applied to a RAW camera sensor. > > Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> > --- > Documentation/driver-api/media/camera-sensor.rst | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst > index 93f4f2536c25..ee4a7fe5f72a 100644 > --- a/Documentation/driver-api/media/camera-sensor.rst > +++ b/Documentation/driver-api/media/camera-sensor.rst > @@ -173,3 +173,19 @@ V4L2_CID_VFLIP controls with the values programmed by the register sequences. > The default values of these controls shall be 0 (disabled). Especially these > controls shall not be inverted, independently of the sensor's mounting > rotation. > + > +Flip handling for raw camera sensors > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Possibly "for colour raw camera sensors". Mono sensors are still raw in that they need processing for black level, lens shading, etc, but they won't change the colour ordering. > + > +Applying vertical and horizontal flips on raw camera sensors inverts the color > +sample reading direction on the sensor's pixel array. This causes the > +re-ordering of the color samples on the sensor's output frame. This *may* cause the re-ordering.... Not all sensors do. Some shift the readout by one line/column to keep the Bayer order the same, and technically should update the selection. OnSemi sensors in particular seem to do this, as do the Sony IMX327/290/462 family. > As an example, a > +raw camera sensor with a Bayer pattern color filter array and a native RGGB > +Bayer order will produce frames with GRBG component ordering when a vertical > +flip is applied. Vertical flip of RGGB would be GBRG as the RG and GB get swapped, not GRBG (which would be horizontal flip). Dave > Camera sensor drivers where inverting the reading order > +direction causes a re-ordering of the color components are requested to register > +the ``V4L2_CID_VFLIP`` and ``V4L2_CID_HFLIP`` controls with the > +``V4L2_CTRL_FLAG_MODIFY_LAYOUT`` flag enabled to notify userspace that enabling > +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. > -- > 2.40.1 >
