usb: gadget: uvc: mark incomplete frames with UVC_STREAM_ERR

If an frame was transmitted incomplete to the host, we set the
UVC_STREAM_ERR bit in the header for the last request that is going
to be queued. This way the host will know that it should drop the
frame instead of trying to display the corrupted content.
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20240214-uvc-error-tag-v1-2-37659a3877fe@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/uvc_video.c

@@ -35,6 +35,9 @@ uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
 
 	data[1] = UVC_STREAM_EOH | video->fid;
 
+	if (video->queue.flags & UVC_QUEUE_DROP_INCOMPLETE)
+		data[1] |= UVC_STREAM_ERR;
+
 	if (video->queue.buf_used == 0 && ts.tv_sec) {
 		/* dwClockFrequency is 48 MHz */
 		u32 pts = ((u64)ts.tv_sec * USEC_PER_SEC + ts.tv_nsec / NSEC_PER_USEC) * 48;