1 files changed, 33 insertions, 4 deletions

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 51f4f653b9..5bebe1460a 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -214,13 +214,13 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,
 		 * Compute a bandwidth estimation by multiplying the frame
 		 * size by the number of video frames per second, divide the
 		 * result by the number of USB frames (or micro-frames for
-		 * high-speed devices) per second and add the UVC header size
-		 * (assumed to be 12 bytes long).
+		 * high- and super-speed devices) per second and add the UVC
+		 * header size (assumed to be 12 bytes long).
 		 */
 		bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp;
 		bandwidth *= 10000000 / interval + 1;
 		bandwidth /= 1000;
-		if (stream->dev->udev->speed == USB_SPEED_HIGH)
+		if (stream->dev->udev->speed >= USB_SPEED_HIGH)
 			bandwidth /= 8;
 		bandwidth += 12;
 
@@ -478,6 +478,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	ktime_t time;
 	u16 host_sof;
 	u16 dev_sof;
+	u32 dev_stc;
 
 	switch (data[1] & (UVC_STREAM_PTS | UVC_STREAM_SCR)) {
 	case UVC_STREAM_PTS | UVC_STREAM_SCR:
@@ -526,6 +527,34 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	if (dev_sof == stream->clock.last_sof)
 		return;
 
+	dev_stc = get_unaligned_le32(&data[header_size - 6]);
+
+	/*
+	 * STC (Source Time Clock) is the clock used by the camera. The UVC 1.5
+	 * standard states that it "must be captured when the first video data
+	 * of a video frame is put on the USB bus". This is generally understood
+	 * as requiring devices to clear the payload header's SCR bit before
+	 * the first packet containing video data.
+	 *
+	 * Most vendors follow that interpretation, but some (namely SunplusIT
+	 * on some devices) always set the `UVC_STREAM_SCR` bit, fill the SCR
+	 * field with 0's,and expect that the driver only processes the SCR if
+	 * there is data in the packet.
+	 *
+	 * Ignore all the hardware timestamp information if we haven't received
+	 * any data for this frame yet, the packet contains no data, and both
+	 * STC and SOF are zero. This heuristics should be safe on compliant
+	 * devices. This should be safe with compliant devices, as in the very
+	 * unlikely case where a UVC 1.1 device would send timing information
+	 * only before the first packet containing data, and both STC and SOF
+	 * happen to be zero for a particular frame, we would only miss one
+	 * clock sample from many and the clock recovery algorithm wouldn't
+	 * suffer from this condition.
+	 */
+	if (buf && buf->bytesused == 0 && len == header_size &&
+	    dev_stc == 0 && dev_sof == 0)
+		return;
+
 	stream->clock.last_sof = dev_sof;
 
 	host_sof = usb_get_current_frame_number(stream->dev->udev);
@@ -575,7 +604,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 	spin_lock_irqsave(&stream->clock.lock, flags);
 
 	sample = &stream->clock.samples[stream->clock.head];
-	sample->dev_stc = get_unaligned_le32(&data[header_size - 6]);
+	sample->dev_stc = dev_stc;
 	sample->dev_sof = dev_sof;
 	sample->host_sof = host_sof;
 	sample->host_time = time;