On Tue, Oct 24, 2023 at 10:11:39AM +0300, Tomi Valkeinen wrote: > On 24/10/2023 03:51, Laurent Pinchart wrote: > > Due to a historical mishap, the v4l2_subdev_frame_interval structure > > is the only part of the V4L2 subdev userspace API that doesn't contain a > > 'which' field. This prevents trying frame intervals using the subdev > > 'TRY' state mechanism. > > > > Add a 'which' field is simple as the structure has 8 reserved fields. > > "Adding" > > > This would however break userspace as the field is currently set to 0, > > corresponding to V4L2_SUBDEV_FORMAT_TRY, while the corresponding ioctls > > currently operate on the 'ACTIVE' state. We thus need to add a new > > That's not the only problem. It wouldn't work even if 0 would be > 'ACTIVE'. The userspace is required to clear the reserved fields, but > the newly added 'which' field is no longer a reserved field, and thus > the userspace might not clear it, leading to it being uninitialized. But > this is solved with the V4L2_SUBDEV_CLIENT_CAP_WHICH_INTERVAL. Yes, I didn't claim it would be the only problem :-) > > subdev client cap, V4L2_SUBDEV_CLIENT_CAP_WHICH_INTERVAL, to indicate > > that userspace is aware of this new field. > > > > All drivers that implement the subdev .g_frame_interval() and > > .s_frame_interval() operations are updated to return -EINVAL when > > .get_frame_interval() and .set_frame_interval() now =). Will be fixed in v2. -- Regards, Laurent Pinchart
