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SubjectRe: [PATCHv4 01/11] videobuf2: add cache management members
On (20/03/09 12:27), Sergey Senozhatsky wrote:
> On (20/03/07 12:47), Hans Verkuil wrote:
> >
> > Create those tests in v4l2-compliance: that's where they belong.
> >
> > You need these tests:
> >
> > For non-MMAP modes:
> >
> > 1) test that V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS is never set.
> >
> > If V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS is not set, then:
> >
> > 1) attempting to use V4L2_FLAG_MEMORY_NON_CONSISTENT will clear the flag
> > upon return (test with both reqbufs and create_bufs).
> > 2) attempting to use V4L2_BUF_FLAG_NO_CACHE_INVALIDATE or V4L2_BUF_FLAG_NO_CACHE_CLEAN
> > will clear those flags upon return (do we actually do that in the patch series?).
>
> NO_CACHE_INVALIDATE/NO_CACHE_CLEAN are cleared in vb2_fill_vb2_v4l2_buffer()
> [as was suggested], then the struct is copied back to user. But I think it
> would be better to clear those flags when we clear
> V4L2_FLAG_MEMORY_NON_CONSISTENT. We have 4 places which do something
> like
> "if !vb2_queue_allows_cache_hints(q) then clear flags bit".

No. I'll just move NO_CACHE_INVALIDATE/NO_CACHE_CLEAN handling to
set_buffer_cache_hints(). This is where we take care of q->memory
and q->allow_cache_hints, this is where we set/clear the
->need_cache_sync flags, this is where we also can clear v4l2_buffer
->flags. Seems like a better place than vb2_fill_vb2_v4l2_buffer().

---
.../media/common/videobuf2/videobuf2-v4l2.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index b4b379f3bf98..0a6bd4a1f58e 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -199,15 +199,6 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b
vbuf->request_fd = -1;
vbuf->is_held = false;

- /*
- * Clear buffer cache flags if queue does not support user space hints.
- * That's to indicate to userspace that these flags won't work.
- */
- if (!vb2_queue_allows_cache_hints(q)) {
- b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
- b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
- }
-
if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
switch (b->memory) {
case VB2_MEMORY_USERPTR:
@@ -368,8 +359,16 @@ static void set_buffer_cache_hints(struct vb2_queue *q,
vb->need_cache_sync_on_prepare = 1;
vb->need_cache_sync_on_finish = 1;

- if (!vb2_queue_allows_cache_hints(q))
+ if (!vb2_queue_allows_cache_hints(q)) {
+ /*
+ * Clear buffer cache flags if queue does not support user
+ * space hints. That's to indicate to userspace that these
+ * flags won't work.
+ */
+ b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
+ b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
return;
+ }

/*
* ->finish() cache sync can be avoided when queue direction is
--
2.25.1
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