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Subject[RFC][PATCH 02/15] videobuf2: handle V4L2 buffer cache flags
Date
Set video buffer cache management flags corresponding to V4L2 cache
flags.

Both ->prepare() and ->finish() cache management hints should be
passed during this stage (buffer preparation), because there is no
other way for user-space to skip ->finish() cache flush.

There are two possible alternative approaches:
- The first one is to move cache sync from ->finish() to dqbuf().
But this breaks some drivers, that need to fix-up buffers before
dequeueing them.

- The second one is to move ->finish() call from ->done() to dqbuf.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
.../media/common/videobuf2/videobuf2-v4l2.c | 22 +++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index e652f4318284..2fccfe2a57f8 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -337,6 +337,27 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b
return 0;
}

+static void set_buffer_cache_hints(struct vb2_queue *q,
+ struct vb2_buffer *vb,
+ struct v4l2_buffer *b)
+{
+ vb->need_cache_sync_on_prepare = 1;
+
+ if (q->dma_dir != DMA_TO_DEVICE)
+ vb->need_cache_sync_on_finish = 1;
+ else
+ vb->need_cache_sync_on_finish = 0;
+
+ if (!q->allow_cache_hints)
+ return;
+
+ if (b->flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
+ vb->need_cache_sync_on_finish = 0;
+
+ if (b->flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN)
+ vb->need_cache_sync_on_prepare = 0;
+}
+
static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
struct v4l2_buffer *b, bool is_prepare,
struct media_request **p_req)
@@ -381,6 +402,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
}

if (!vb->prepared) {
+ set_buffer_cache_hints(q, vb, b);
/* Copy relevant information provided by the userspace */
memset(vbuf->planes, 0,
sizeof(vbuf->planes[0]) * vb->num_planes);
--
2.24.1.735.g03f4e72817-goog
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