From:   Ricardo Ribalda <ribalda@chromium.org>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Tomasz Figa <tfiga@chromium.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        "hn . chen" <hn.chen@sunplusit.com>
Cc:     Ricardo Ribalda <ribalda@chromium.org>
Subject: [PATCH 1/8] media: uvc: Extend documentation of uvc_video_clock_decode()
Date:   Thu, 18 Nov 2021 22:09:06 +0000
Message-Id: <20211118220913.299978-2-ribalda@chromium.org>
In-Reply-To: <20211118220913.299978-1-ribalda@chromium.org>
References: <20211118220913.299978-1-ribalda@chromium.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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Make a explicit reference to uvc 1.5, explaining how the algorithm
supports the different behaviour of uvc 1.1 and 1.5.

Tested-by: hn.chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_video.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 9f37eaf28ce7e..4b5f7e156b0de 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -510,6 +510,9 @@ 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.
+	 * This filtering is also needed for supporting UVC 1.5. Where all the
+	 * data packages 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)
-- 
2.34.0.rc2.393.gf8c9666880-goog