[media] uvcvideo: Generate discontinuous sequence numbers when frames are lost

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.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/video/uvc/uvc_queue.c b/drivers/media/video/uvc/uvc_queue.c
index d27a315..ed6d544 100644 (file)
--- 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..5555f01 100644 (file)
--- 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 = -1;
        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 (file)
--- 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;
 };