media: media/v4l2: remove V4L2_FLAG_MEMORY_NON_CONSISTENT flag

The patch partially reverts some of the UAPI bits of the buffer
cache management hints. Namely, the queue consistency (memory
coherency) user-space hint because, as it turned out, the kernel
implementation of this feature was misusing DMA_ATTR_NON_CONSISTENT.

The patch reverts both kernel and user space parts: removes the
DMA consistency attr functions, rolls back changes to v4l2_requestbuffers,
v4l2_create_buffers structures and corresponding UAPI functions
(plus compat32 layer) and cleans up the documentation.

[hverkuil: fixed a few typos in the commit log]
[hverkuil: fixed vb2_core_reqbufs call in drivers/media/dvb-core/dvb_vb2.c]
[mchehab: fixed a typo in the commit log: revers->reverts]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

1 files changed, 0 insertions, 19 deletions

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
index ec3446cc45b8..7b1b86ec942d 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
@@ -42,11 +42,6 @@ struct vb2_dc_buf {
 	struct dma_buf_attachment	*db_attach;
 };
 
-static inline bool vb2_dc_buffer_consistent(unsigned long attr)
-{
-	return !(attr & DMA_ATTR_NON_CONSISTENT);
-}
-
 /*********************************************/
 /*        scatterlist table functions        */
 /*********************************************/
@@ -341,13 +336,6 @@ static int
 vb2_dc_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
 				   enum dma_data_direction direction)
 {
-	struct vb2_dc_buf *buf = dbuf->priv;
-	struct sg_table *sgt = buf->dma_sgt;
-
-	if (vb2_dc_buffer_consistent(buf->attrs))
-		return 0;
-
-	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 	return 0;
 }
 
@@ -355,13 +343,6 @@ static int
 vb2_dc_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
 				 enum dma_data_direction direction)
 {
-	struct vb2_dc_buf *buf = dbuf->priv;
-	struct sg_table *sgt = buf->dma_sgt;
-
-	if (vb2_dc_buffer_consistent(buf->attrs))
-		return 0;
-
-	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 	return 0;
 }