| Message ID | 20191217032034.54897-4-senozhatsky@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Implement V4L2_BUF_FLAG_NO_CACHE_* flags | expand |
On 12/17/19 4:20 AM, Sergey Senozhatsky wrote: > By setting or clearing V4L2_FLAG_MEMORY_NON_CONSISTENT flag > user-space should be able to set or clear queue's NON_CONSISTENT > ->dma_attrs. Queue's ->dma_attrs are passed to the underlying > allocator in __vb2_buf_mem_alloc(), so user-space will be able > to request consistent or non-consistent memory allocations. > > Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> > --- > Documentation/media/uapi/v4l/buffer.rst | 19 +++++++++++++++++++ > include/uapi/linux/videodev2.h | 2 ++ > 2 files changed, 21 insertions(+) > > diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst > index 9149b57728e5..b08b5609f5f3 100644 > --- a/Documentation/media/uapi/v4l/buffer.rst > +++ b/Documentation/media/uapi/v4l/buffer.rst > @@ -705,6 +705,25 @@ Buffer Flags > > .. c:type:: v4l2_memory > > +Memory Consistency Flags > +======================== > + > +.. tabularcolumns:: |p{7.0cm}|p{2.2cm}|p{8.3cm}| > + > +.. cssclass:: longtable > + > +.. flat-table:: > + :header-rows: 0 > + :stub-columns: 0 > + :widths: 3 1 4 > + > + * .. _`V4L2_FLAG_MEMORY_NON_CONSISTENT`: > + > + - ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` > + - 0x00000001 > + - Set DMA_ATTR_NON_CONSISTENT queue memory consistency bit, > + so all queue buffers may be allocated in non-consistent memory. This needs much more extensive documentation. This is a userspace API, and it shouldn't refer to a kernelspace API. Instead, explain what it means from a user perspective. Also, how does this relate to the cache buffer flags? These things are tricky, so it is worth spending some time on writing good documentation. Regards, Hans > + > enum v4l2_memory > ================ > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 04481c717fee..d352997f2b62 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -189,6 +189,8 @@ enum v4l2_memory { > V4L2_MEMORY_DMABUF = 4, > }; > > +#define V4L2_FLAG_MEMORY_NON_CONSISTENT (1 << 0) > + > /* see also http://vektor.theorem.ca/graphics/ycbcr/ */ > enum v4l2_colorspace { > /* >
On (20/01/10 10:36), Hans Verkuil wrote: [..] > > diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst > > index 9149b57728e5..b08b5609f5f3 100644 > > --- a/Documentation/media/uapi/v4l/buffer.rst > > +++ b/Documentation/media/uapi/v4l/buffer.rst > > @@ -705,6 +705,25 @@ Buffer Flags > > > > .. c:type:: v4l2_memory > > > > +Memory Consistency Flags > > +======================== > > + > > +.. tabularcolumns:: |p{7.0cm}|p{2.2cm}|p{8.3cm}| > > + > > +.. cssclass:: longtable > > + > > +.. flat-table:: > > + :header-rows: 0 > > + :stub-columns: 0 > > + :widths: 3 1 4 > > + > > + * .. _`V4L2_FLAG_MEMORY_NON_CONSISTENT`: > > + > > + - ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` > > + - 0x00000001 > > + - Set DMA_ATTR_NON_CONSISTENT queue memory consistency bit, > > + so all queue buffers may be allocated in non-consistent memory. > > This needs much more extensive documentation. This is a userspace API, > and it shouldn't refer to a kernelspace API. Instead, explain what it > means from a user perspective. Also, how does this relate to the cache > buffer flags? > > These things are tricky, so it is worth spending some time on writing > good documentation. Agreed. I'll give it a shot, will try to improve it. -ss
diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst index 9149b57728e5..b08b5609f5f3 100644 --- a/Documentation/media/uapi/v4l/buffer.rst +++ b/Documentation/media/uapi/v4l/buffer.rst @@ -705,6 +705,25 @@ Buffer Flags .. c:type:: v4l2_memory +Memory Consistency Flags +======================== + +.. tabularcolumns:: |p{7.0cm}|p{2.2cm}|p{8.3cm}| + +.. cssclass:: longtable + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + * .. _`V4L2_FLAG_MEMORY_NON_CONSISTENT`: + + - ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` + - 0x00000001 + - Set DMA_ATTR_NON_CONSISTENT queue memory consistency bit, + so all queue buffers may be allocated in non-consistent memory. + enum v4l2_memory ================ diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 04481c717fee..d352997f2b62 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -189,6 +189,8 @@ enum v4l2_memory { V4L2_MEMORY_DMABUF = 4, }; +#define V4L2_FLAG_MEMORY_NON_CONSISTENT (1 << 0) + /* see also http://vektor.theorem.ca/graphics/ycbcr/ */ enum v4l2_colorspace { /*
By setting or clearing V4L2_FLAG_MEMORY_NON_CONSISTENT flag user-space should be able to set or clear queue's NON_CONSISTENT ->dma_attrs. Queue's ->dma_attrs are passed to the underlying allocator in __vb2_buf_mem_alloc(), so user-space will be able to request consistent or non-consistent memory allocations. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- Documentation/media/uapi/v4l/buffer.rst | 19 +++++++++++++++++++ include/uapi/linux/videodev2.h | 2 ++ 2 files changed, 21 insertions(+)