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[v3,1/8] media: uvcvideo: Extend documentation of uvc_video_clock_decode()

Message ID 20220920-resend-hwtimestamp-v3-1-db9faee7f47d@chromium.org
State New
Headers
Series uvcvideo: Fixes for hw timestamping |

Commit Message

Ricardo Ribalda Jan. 4, 2023, 10:45 a.m. UTC 
  Make an explicit reference to UVC 1.5, explaining how the algorithm
supports the different behaviour of UVC 1.1 and 1.5.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index d2eb9066e4dc..def079c7a6fd 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -516,7 +516,9 @@  uvc_video_clock_decode(struct uvc_streaming *stream, struct uvc_buffer *buf,
 
 	/*
 	 * To limit the amount of data, drop SCRs with an SOF identical to the
-	 * previous one.
+	 * previous one. This filtering is also needed to support UVC 1.5, where
+	 * all the data packets of the same frame contains the same SOF. In that
+	 * case only the first one will match the host_sof.
 	 */
 	dev_sof = get_unaligned_le16(&data[header_size - 2]);
 	if (dev_sof == stream->clock.last_sof)