[RFC][PATCHv2 11/12] videobuf2: add begin/end cpu_access callbacks to dma-sg

[Sergey Senozhatsky]

Provide begin_cpu_access() and end_cpu_access() dma_buf_ops
callbacks for cache synchronisation on exported buffers.

V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
dma-sg allocates memory using the page allocator directly, so
there is no memory consistency guarantee.

Change-Id: Ia0d9d72a8c2a9fe3264ac148f59201573289ed2c
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 .../media/common/videobuf2/videobuf2-dma-sg.c | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
index 6db60e9d5183..bfc99a0cb7b9 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
@@ -470,6 +470,26 @@ static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 	vb2_dma_sg_put(dbuf->priv);
 }
 
+static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
+					enum dma_data_direction direction)
+{
+	struct vb2_dma_sg_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+	return 0;
+}
+
+static int vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
+					enum dma_data_direction direction)
+{
+	struct vb2_dma_sg_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+	return 0;
+}
+
 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 {
 	struct vb2_dma_sg_buf *buf = dbuf->priv;
@@ -488,6 +508,8 @@ static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 	.detach = vb2_dma_sg_dmabuf_ops_detach,
 	.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 	.unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
+	.begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
+	.end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
 	.vmap = vb2_dma_sg_dmabuf_ops_vmap,
 	.mmap = vb2_dma_sg_dmabuf_ops_mmap,
 	.release = vb2_dma_sg_dmabuf_ops_release,
-- 
2.25.0.341.g760bfbb309-goog