We need a combination of two factors in order to permit modification
of queue's memory consistency attribute in set_queue_consistency():
(1) queue should allow user-space cache hints
(2) queue should be used for MMAP-ed I/O
Therefore the code in videobuf2 core looks as follows:
q->memory = req->memory;
set_queue_consistency(q, consistent);
This works when we do something like this (suppose that queue allows
cache hints)
reqbufs.memory = V4L2_MEMORY_DMABUF;
reqbufs.flags = 0;
doioctl(node, VIDIOC_REQBUFS, &reqbufs);
reqbufs.memory = V4L2_MEMORY_MMAP;
reqbufs.flags = V4L2_FLAG_MEMORY_NON_CONSISTENT;
doioctl(node, VIDIOC_REQBUFS, &reqbufs);
However, this doesn't work the other way around
reqbufs.memory = V4L2_MEMORY_MMAP;
reqbufs.flags = V4L2_FLAG_MEMORY_NON_CONSISTENT;
doioctl(node, VIDIOC_REQBUFS, &reqbufs);
reqbufs.memory = V4L2_MEMORY_DMABUF;
reqbufs.flags = 0;
doioctl(node, VIDIOC_REQBUFS, &reqbufs);
because __vb2_queue_free() doesn't clear queue's ->dma_attrs
once its don't freeing queue buffers, and by the time we call
set_queue_consistency() the queue is DMABUF so (2) is false
and we never clear the stale consistency attribute.
Re-implement set_queue_consistency() - it must always clear
queue's non-consistency attr and set it only if (1) and (2).
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
---
drivers/media/common/videobuf2/videobuf2-core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 7e081716b8da..37d0186ba330 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -704,12 +704,11 @@ EXPORT_SYMBOL(vb2_verify_memory_type);
static void set_queue_consistency(struct vb2_queue *q, bool consistent_mem)
{
+ q->dma_attrs &= ~DMA_ATTR_NON_CONSISTENT;
+
if (!vb2_queue_allows_cache_hints(q))
return;
-
- if (consistent_mem)
- q->dma_attrs &= ~DMA_ATTR_NON_CONSISTENT;
- else
+ if (!consistent_mem)
q->dma_attrs |= DMA_ATTR_NON_CONSISTENT;
}
--
2.27.0
