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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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