On Tue, Sep 3, 2019 at 1:43 AM Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > > Hi Jacopo, > > On Mon, Sep 02, 2019 at 01:20:49PM +0200, Jacopo Mondi wrote: > > On Tue, Aug 27, 2019 at 03:51:32PM +0300, Laurent Pinchart wrote: > > > On Tue, Aug 27, 2019 at 11:23:29AM +0200, Jacopo Mondi wrote: > > >> Add documentation for the V4L2_CID_CAMERA_SENSOR_ROTATION camera > > >> control. The newly added read-only control reports the camera device > > >> mounting rotation. > > >> > > >> Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx> > > >> --- > > >> Documentation/media/uapi/v4l/ext-ctrls-camera.rst | 9 +++++++++ > > >> 1 file changed, 9 insertions(+) > > >> > > >> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-camera.rst b/Documentation/media/uapi/v4l/ext-ctrls-camera.rst > > >> index ecf151f3f0f4..03d1c23d18f7 100644 > > >> --- a/Documentation/media/uapi/v4l/ext-ctrls-camera.rst > > >> +++ b/Documentation/media/uapi/v4l/ext-ctrls-camera.rst > > >> @@ -544,6 +544,15 @@ enum v4l2_scene_mode - > > >> > > >> > > >> > > >> +``V4L2_CID_CAMERA_SENSOR_ROTATION (integer)`` > > >> + This read-only control describes the camera sensor orientation by > > >> + reporting its mounting rotation in respect to the device intended usage > > >> + orientation, expressed in counter clockwise degrees. The control value is > > > > > > Counter clockwise relative to what ? :-) > > > > I think it is expressed in the previous line: > > "mounting rotation in respect to the device intended usage > > orientation, expressed in counter clockwise degrees" > > > > Would you prefer to have this re-phrased as: > > > > This read-only control describes the camera sensor orientation > > expressed as rotation in counter clockwise degrees in respect to > > the device intended usage orientation. > > > > ? > > Rotation is expressed in degrees around an axis, which is itself > expressed as a vector. It's pretty intuitive that the rotation vector > should be perpendicular to the plane of the sensor (which itself should > be parallel to the plane of the device side on which it is mounted, as > expressed by the location property), but there are still two possible > directions for the vector, facing in the same direction as the sensor or > the opposite direction. Unless there's a good reason to do so, I would > use the same direction as the one defined by Android. I don't know what > direction that is though :-) I don't think Android exposes camera rotation to the layers above the HAL. The stream is expected to be pre-rotated by the HAL, taking into account the desired target rotation of the stream itself [1]. [1] https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/camera3.h#1428 That said, Android seems to use "degrees counterclockwise" for rotations. Best regards, Tomasz
