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

From: Laurent Pinchart
Date: Sun Mar 23 2014 - 11:31:54 EST


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@xxxxxxxxxxxxxxxx>
---
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);
+
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;

vb2_set_plane_payload(&buf->buf, 0, buf->bytesused);
vb2_buffer_done(&buf->buf, VB2_BUF_STATE_DONE);
--
1.8.3.2

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