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SubjectRe: [PATCH 1/2] usb: gadget: uvc: Switch to monotonic clock for buffer timestamps
Hi Laurent,

I have a few comments:

On 03/23/2014 04:32 PM, Laurent Pinchart wrote:
> The wall time clock isn't useful for applications as it can jump around
> due to time adjustement. Switch to the monotonic clock.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
> drivers/usb/gadget/uvc_queue.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/gadget/uvc_queue.c b/drivers/usb/gadget/uvc_queue.c
> index 0bb5d50..d4561ba 100644
> --- a/drivers/usb/gadget/uvc_queue.c
> +++ b/drivers/usb/gadget/uvc_queue.c
> @@ -364,6 +364,7 @@ static struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> struct uvc_buffer *buf)
> {
> struct uvc_buffer *nextbuf;
> + struct timespec ts;
>
> if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
> buf->length != buf->bytesused) {
> @@ -379,14 +380,11 @@ static struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> else
> nextbuf = NULL;
>
> - /*
> - * FIXME: with videobuf2, the sequence number or timestamp fields
> - * are valid only for video capture devices and the UVC gadget usually
> - * is a video output device. Keeping these until the specs are clear on
> - * this aspect.
> - */
> + ktime_get_ts(&ts);

Why not use the v4l2-common.c helper v4l2_get_timestamp()?

> +
> buf->buf.v4l2_buf.sequence = queue->sequence++;
> - do_gettimeofday(&buf->buf.v4l2_buf.timestamp);
> + buf->buf.v4l2_buf.timestamp.tv_sec = ts.tv_sec;
> + buf->buf.v4l2_buf.timestamp.tv_usec = ts.tv_nsec / NSEC_PER_USEC;

You should also add:

buf->buf.v4l2_buf.field = V4L2_FIELD_NONE;

I noticed that that was never set, which is wrong.

Regards,

Hans

>
> vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
> vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);
>



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