Add support for the frame_sync event, so user-space can become aware earlier of new frames. Suggested-by: Esker Wong <esker@xxxxxxxxxxxx> Tested-by: Esker Wong <esker@xxxxxxxxxxxx> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> --- We have measured a latency of around 30msecs between frame sync and dqbuf. --- Changes in v2: - Suggested by Laurent. Split sequence++ and event init. - Link to v1: https://lore.kernel.org/r/20231020-uvc-event-v1-1-3baa0e9f6952@xxxxxxxxxxxx --- drivers/media/usb/uvc/uvc_v4l2.c | 2 ++ drivers/media/usb/uvc/uvc_video.c | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c index f4988f03640a..9f3fb5fd2375 100644 --- a/drivers/media/usb/uvc/uvc_v4l2.c +++ b/drivers/media/usb/uvc/uvc_v4l2.c @@ -1352,6 +1352,8 @@ static int uvc_ioctl_subscribe_event(struct v4l2_fh *fh, switch (sub->type) { case V4L2_EVENT_CTRL: return v4l2_event_subscribe(fh, sub, 0, &uvc_ctrl_sub_ev_ops); + case V4L2_EVENT_FRAME_SYNC: + return v4l2_event_subscribe(fh, sub, 0, NULL); default: return -EINVAL; } diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index 28dde08ec6c5..4f3a510ca4fe 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -1073,9 +1073,16 @@ static int uvc_video_decode_start(struct uvc_streaming *stream, * that discontinuous sequence numbers always indicate lost frames. */ if (stream->last_fid != fid) { + struct v4l2_event event = { + .type = V4L2_EVENT_FRAME_SYNC, + }; + stream->sequence++; if (stream->sequence) uvc_video_stats_update(stream); + + event.u.frame_sync.frame_sequence = stream->sequence, + v4l2_event_queue(&stream->vdev, &event); } uvc_video_clock_decode(stream, buf, data, len); --- base-commit: ce55c22ec8b223a90ff3e084d842f73cfba35588 change-id: 20231020-uvc-event-d3d1bbbdcb2f Best regards, -- Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
