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Subject[PATCH] [media] uvcvideo: Fix clock param realtime setting
Date
timestamps in v4l2 buffers returned to userspace are updated in
uvc_video_clock_update() which uses timestamps fetched from
uvc_video_clock_decode() by calling unconditionally ktime_get_ts().

Hence setting the module clock param to realtime have no effect
before this patch.

This has been tested with ffmpeg:

ffmpeg -y -f v4l2 -input_format yuyv422 -video_size 640x480 -framerate 30 -i /dev/video0 \
-f alsa -acodec pcm_s16le -ar 16000 -ac 1 -i default \
-c:v libx264 -preset ultrafast \
-c:a libfdk_aac \
out.mkv

and inspecting the v4l2 input starting timestamp.

Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Cc: Stable <stable@vger.kernel.org>
---
drivers/media/usb/uvc/uvc_video.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 898c208..c79db33 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -361,6 +361,14 @@ static int uvc_commit_video(struct uvc_streaming *stream,
* Clocks and timestamps
*/

+static inline void uvc_video_get_ts(struct timespec *ts)
+{
+ if (uvc_clock_param == CLOCK_MONOTONIC)
+ ktime_get_ts(ts);
+ else
+ ktime_get_real_ts(ts);
+}
+
static void
uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
const __u8 *data, int len)
@@ -420,7 +428,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
stream->clock.last_sof = dev_sof;

host_sof = usb_get_current_frame_number(stream->dev->udev);
- ktime_get_ts(&ts);
+ uvc_video_get_ts(&ts);

/* The UVC specification allows device implementations that can't obtain
* the USB frame number to keep their own frame counters as long as they
@@ -1011,10 +1019,7 @@ static int uvc_video_decode_start(struct uvc_streaming *stream,
return -ENODATA;
}

- if (uvc_clock_param == CLOCK_MONOTONIC)
- ktime_get_ts(&ts);
- else
- ktime_get_real_ts(&ts);
+ uvc_video_get_ts(&ts);

buf->buf.v4l2_buf.sequence = stream->sequence;
buf->buf.v4l2_buf.timestamp.tv_sec = ts.tv_sec;
--
1.9.1


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