On (20/01/10 10:55), Hans Verkuil wrote: > On 12/17/19 4:20 AM, Sergey Senozhatsky wrote: > > This patch lets user-space to request a non-consistent memory > > allocation during REQBUFS ioctl call. We use one bit of a > > ->reserved[1] member of struct v4l2_requestbuffers, which is > > now renamed to ->flags. > > > > There is just 1 four-byte reserved area in v4l2_requestbuffers > > struct, therefore for backward compatibility ->reserved and > > ->flags were put into anonymous union. > > > > Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> > > --- > > Documentation/media/uapi/v4l/vidioc-reqbufs.rst | 14 ++++++++++++-- > > drivers/media/common/videobuf2/videobuf2-v4l2.c | 14 ++++++++++++-- > > drivers/media/v4l2-core/v4l2-ioctl.c | 3 --- > > include/uapi/linux/videodev2.h | 5 ++++- > > 4 files changed, 28 insertions(+), 8 deletions(-) > > > > diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > > index d0c643db477a..9b69a61d9fd4 100644 > > --- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > > +++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > > @@ -112,10 +112,20 @@ aborting or finishing any DMA in progress, an implicit > > ``V4L2_MEMORY_MMAP`` and ``type`` set to the buffer type. This will > > free any previously allocated buffers, so this is typically something > > that will be done at the start of the application. > > - * - __u32 > > + * - union > > + - (anonymous) > > + * - > > + - __u32 > > + - ``flags``\ [1] > > + - Specifies additional buffer management attributes. E.g. when > > + ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` set vb2 backends may be allocated > > + in non-consistent memory. > > This should link to the table with these memory flags, rather than > effectively documenting V4L2_FLAG_MEMORY_NON_CONSISTENT again. OK. > You also probably meant "vb2 buffers" rather than "vb2 backends". Thanks. > > > + * - > > + - __u32 > > - ``reserved``\ [1] > > - A place holder for future extensions. Drivers and applications > > - must set the array to zero. > > + must set the array to zero, unless application wants to specify > > + buffer management ``flags``. > > I think support for this flag should be signaled as a V4L2_BUF_CAP capability. > If the capability is not set, then vb2 should set 'flags' to 0 to preserve the > old 'Drivers and applications must set the array to zero' behavior. The patch set adds V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS towards the end of the series, I guess I can shuffle the patches and change the wording here. > The documentation for 'reserved[1]' should be changed to something like: > > Kept for backwards compatibility. Use ``flags`` instead. OK. -ss
