linux-kernel - [PATCH] media: vb2: always set buffer cache sync hints

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Message-Id: <20201127094136.1051071-1-sergey.senozhatsky@gmail.com>
Date:   Fri, 27 Nov 2020 18:41:36 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH] media: vb2: always set buffer cache sync hints

We need to always set ->need_cache_sync_on_prepare and
->need_cache_sync_on_finish when we initialize vb2 buffer.

Currently these flags are set/adjusted only in V4L2's
vb2_queue_or_prepare_buf(), which means that for the code
paths that don't use V4L2 vb2 will always tell videobuf2
core to skip ->prepare() and ->finish() cache syncs/flushes.

This is a quick solution that should do the trick. The
proper fix, however, is much more complicated and requires
a rather big videobuf2 refactoring - we need to move cache
sync/flush decision making out of core videobuf2 to the
allocators.

Reported-by: Tomasz Figa <tfiga@...omium.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 5499013cf82e..14a26888a892 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -414,6 +414,8 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 		vb->index = q->num_buffers + buffer;
 		vb->type = q->type;
 		vb->memory = memory;
+		vb->need_cache_sync_on_prepare = 1;
+		vb->need_cache_sync_on_finish = 1;
 		for (plane = 0; plane < num_planes; ++plane) {
 			vb->planes[plane].length = plane_sizes[plane];
 			vb->planes[plane].min_length = plane_sizes[plane];
-- 
2.29.2