Increase the sequence number of the v4l2_buffer structure regardless of
any buffer states, so that discontinuous sequence numbers allow
applications to detect lost video frames.
Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
---
drivers/media/video/uvc/uvc_queue.c | 7 +------
drivers/media/video/uvc/uvc_video.c | 9 +++++++++
drivers/media/video/uvc/uvcvideo.h | 2 +-
3 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/media/video/uvc/uvc_queue.c
b/drivers/media/video/uvc/uvc_queue.c
index d27a315..ed6d544 100644
--- a/drivers/media/video/uvc/uvc_queue.c
+++ b/drivers/media/video/uvc/uvc_queue.c
@@ -135,7 +135,6 @@ int uvc_alloc_buffers(struct uvc_video_queue *queue,
unsigned int nbuffers,
queue->buffer[i].buf.m.offset = i * bufsize;
queue->buffer[i].buf.length = buflength;
queue->buffer[i].buf.type = queue->type;
- queue->buffer[i].buf.sequence = 0;
queue->buffer[i].buf.field = V4L2_FIELD_NONE;
queue->buffer[i].buf.memory = V4L2_MEMORY_MMAP;
queue->buffer[i].buf.flags = 0;
@@ -410,8 +409,7 @@ done:
* state can be properly initialized before buffers are accessed from the
* interrupt handler.
*
- * Enabling the video queue initializes parameters (such as sequence number,
- * sync pattern, ...). If the queue is already enabled, return -EBUSY.
+ * Enabling the video queue returns -EBUSY if the queue is already enabled.
*
* Disabling the video queue cancels the queue and removes all buffers from
* the main queue.
@@ -430,7 +428,6 @@ int uvc_queue_enable(struct uvc_video_queue *queue, int
enable)
ret = -EBUSY;
goto done;
}
- queue->sequence = 0;
queue->flags |= UVC_QUEUE_STREAMING;
queue->buf_used = 0;
} else {
@@ -510,8 +507,6 @@ struct uvc_buffer *uvc_queue_next_buffer(struct
uvc_video_queue *queue,
nextbuf = NULL;
spin_unlock_irqrestore(&queue->irqlock, flags);
- buf->buf.sequence = queue->sequence++;
-
wake_up(&buf->wait);
return nextbuf;
}
diff --git a/drivers/media/video/uvc/uvc_video.c
b/drivers/media/video/uvc/uvc_video.c
index 5a2022c..39d4e70 100644
--- a/drivers/media/video/uvc/uvc_video.c
+++ b/drivers/media/video/uvc/uvc_video.c
@@ -427,6 +427,12 @@ static int uvc_video_decode_start(struct uvc_streaming
*stream,
fid = data[1] & UVC_STREAM_FID;
+ /* Increase the sequence number regardless of any buffer states, so
+ * that discontinuous sequence numbers always indicate lost frames.
+ */
+ if (stream->last_fid != fid)
+ stream->sequence++;
+
/* Store the payload FID bit and return immediately when the buffer is
* NULL.
*/
@@ -460,6 +466,7 @@ static int uvc_video_decode_start(struct uvc_streaming
*stream,
else
ktime_get_real_ts(&ts);
+ buf->buf.sequence = stream->sequence;
buf->buf.timestamp.tv_sec = ts.tv_sec;
buf->buf.timestamp.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
@@ -721,6 +728,7 @@ static void uvc_video_encode_bulk(struct urb *urb, struct
uvc_streaming *stream,
if (buf->buf.bytesused == stream->queue.buf_used) {
stream->queue.buf_used = 0;
buf->state = UVC_BUF_STATE_READY;
+ buf->buf.sequence = stream->sequence++;
uvc_queue_next_buffer(&stream->queue, buf);
stream->last_fid ^= UVC_STREAM_FID;
}
@@ -979,6 +987,7 @@ static int uvc_init_video(struct uvc_streaming *stream,
gfp_t gfp_flags)
unsigned int i;
int ret;
+ stream->sequence = 0;
stream->last_fid = -1;
stream->bulk.header_size = 0;
stream->bulk.skip_payload = 0;
diff --git a/drivers/media/video/uvc/uvcvideo.h
b/drivers/media/video/uvc/uvcvideo.h
index 892e0e5..f890133 100644
--- a/drivers/media/video/uvc/uvcvideo.h
+++ b/drivers/media/video/uvc/uvcvideo.h
@@ -392,7 +392,6 @@ struct uvc_video_queue {
void *mem;
unsigned int flags;
- __u32 sequence;
unsigned int count;
unsigned int buf_size;
@@ -458,6 +457,7 @@ struct uvc_streaming {
dma_addr_t urb_dma[UVC_URBS];
unsigned int urb_size;
+ __u32 sequence;
__u8 last_fid;
};
--
1.7.2.2
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