linux-kernel - [PATCH v4 04/24] media: h264: Avoid wrapping long_term_frame

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Message-Id: <20220426125751.108293-5-nicolas.dufresne@collabora.com>
Date:   Tue, 26 Apr 2022 08:57:30 -0400
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     nicolas@...fresne.ca, linux-media@...r.kernel.org,
        Sebastian Fricke <sebastian.fricke@...labora.com>,
        Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 04/24] media: h264: Avoid wrapping long_term_frame_idx

For long term references, frame_num is set to long_term_frame_idx which
does not require wrapping. This is fixed by observation, no directly
related issue have been found yet.

Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@...labora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
---
 drivers/media/v4l2-core/v4l2-h264.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-h264.c b/drivers/media/v4l2-core/v4l2-h264.c
index 5633a242520a..ac47519a9fbe 100644
--- a/drivers/media/v4l2-core/v4l2-h264.c
+++ b/drivers/media/v4l2-core/v4l2-h264.c
@@ -57,8 +57,10 @@ v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
 		 * '8.2.4.1 Decoding process for picture numbers' of the spec.
 		 * TODO: This logic will have to be adjusted when we start
 		 * supporting interlaced content.
+		 * For long term references, frame_num is set to
+		 * long_term_frame_idx which requires no wrapping.
 		 */
-		if (dpb[i].frame_num > cur_frame_num)
+		if (!b->refs[i].longterm && dpb[i].frame_num > cur_frame_num)
 			b->refs[i].frame_num = (int)dpb[i].frame_num -
 					       max_frame_num;
 		else
-- 
2.34.1