2 files changed, 23 insertions, 0 deletions

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 5df8f61d39cd..aebcf9b25a16 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -471,8 +471,29 @@ static void uvc_video_clock_add_sample(struct uvc_clock *clock,
 {
 	unsigned long flags;
 
+	/*
+	 * If we write new data on the position where we had the last
+	 * overflow, remove the overflow pointer. There is no SOF overflow
+	 * in the whole circular buffer.
+	 */
+	if (clock->head == clock->last_sof_overflow)
+		clock->last_sof_overflow = -1;
+
 	spin_lock_irqsave(&clock->lock, flags);
 
+	if (clock->count > 0 && clock->last_sof > sample->dev_sof) {
+		/*
+		 * Remove data from the circular buffer that is older than the
+		 * last SOF overflow. We only support one SOF overflow per
+		 * circular buffer.
+		 */
+		if (clock->last_sof_overflow != -1)
+			clock->count = (clock->head - clock->last_sof_overflow
+					+ clock->size) % clock->size;
+		clock->last_sof_overflow = clock->head;
+	}
+
+	/* Add sample. */
 	clock->samples[clock->head] = *sample;
 	clock->head = (clock->head + 1) % clock->size;
 	clock->count = min(clock->count + 1, clock->size);
@@ -616,6 +637,7 @@ static void uvc_video_clock_reset(struct uvc_clock *clock)
 	clock->head = 0;
 	clock->count = 0;
 	clock->last_sof = -1;
+	clock->last_sof_overflow = -1;
 	clock->sof_offset = -1;
 }
 
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index e5b12717016f..f21207debd54 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -501,6 +501,7 @@ struct uvc_streaming {
 		unsigned int head;
 		unsigned int count;
 		unsigned int size;
+		unsigned int last_sof_overflow;
 
 		u16 last_sof;
 		u16 sof_offset;