| Message ID | 20200302041213.27662-4-senozhatsky@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Implement V4L2_BUF_FLAG_NO_CACHE_* flags | expand |
On 02/03/2020 05:12, 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 thus user-space is able > to request vb2 buffer's memory to be either consistent (coherent) > or non-consistent. > > The patch set also adds a corresponding capability flag: > fill_buf_caps() reports V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS when > queue supports user-space cache management hints. When building the docs I got a bunch of reference errors. This patch fixes those: ----------------------------------------------- diff --git b/Documentation/media/uapi/v4l/buffer.rst a/Documentation/media/uapi/v4l/buffer.rst index 8084e3f2a58d..82bad4dbec16 100644 --- b/Documentation/media/uapi/v4l/buffer.rst +++ a/Documentation/media/uapi/v4l/buffer.rst @@ -695,7 +695,7 @@ Memory Consistency Flags :stub-columns: 0 :widths: 3 1 4 - * .. _`V4L2_FLAG_MEMORY_NON_CONSISTENT`: + * .. _`V4L2-FLAG-MEMORY-NON-CONSISTENT`: - ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` - 0x00000001 @@ -709,7 +709,9 @@ Memory Consistency Flags consistency is needed. If this flag is set V4L2 will attempt to allocate the buffer in non-consistent memory. The flag takes effect only if the buffer is used for :ref:`memory mapping <mmap>` I/O and the - queue reports the :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability. + queue reports the + :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS <V4L2-BUF-CAP-SUPPORTS-CACHE-HINTS>` + capability. .. c:type:: v4l2_memory diff --git b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst index faf0df4f9bb6..1c0299424fbc 100644 --- b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst +++ a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst @@ -133,6 +133,7 @@ aborting or finishing any DMA in progress, an implicit .. _V4L2-BUF-CAP-SUPPORTS-REQUESTS: .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS: .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF: +.. _V4L2-BUF-CAP-SUPPORTS-CACHE-HINTS: .. cssclass:: longtable @@ -166,9 +167,10 @@ aborting or finishing any DMA in progress, an implicit * - ``V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS`` - 0x00000040 - Set when the queue/buffer supports memory consistency and cache - management hints. See :ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT`, - :ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE` and - :ref:`V4L2_BUF_FLAG_NO_CACHE_CLEAN`. + management hints. See + :ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT <V4L2-FLAG-MEMORY-NON-CONSISTENT>`, + :ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE <V4L2-BUF-FLAG-NO-CACHE-INVALIDATE>` and + :ref:`V4L2_BUF_FLAG_NO_CACHE_CLEAN <V4L2-BUF-FLAG-NO-CACHE-CLEAN>`. Return Value ----------------------------------------------- Please fold that in this patch. Regards, Hans > > Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> > --- > Documentation/media/uapi/v4l/buffer.rst | 29 +++++++++++++++++++ > .../media/uapi/v4l/vidioc-reqbufs.rst | 7 +++++ > .../media/common/videobuf2/videobuf2-v4l2.c | 2 ++ > include/uapi/linux/videodev2.h | 3 ++ > 4 files changed, 41 insertions(+) > > diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst > index 3112300c2fa0..8084e3f2a58d 100644 > --- a/Documentation/media/uapi/v4l/buffer.rst > +++ b/Documentation/media/uapi/v4l/buffer.rst > @@ -681,6 +681,35 @@ Buffer Flags > > \normalsize > > +.. _memory-flags: > + > +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 > + - A buffer is allocated either in consistent (it will be automatically > + coherent between the CPU and the bus) or non-consistent memory. The > + latter can provide performance gains, for instance the CPU cache > + sync/flush operations can be avoided if the buffer is accessed by the > + corresponding device only and the CPU does not read/write to/from that > + buffer. However, this requires extra care from the driver -- it must > + guarantee memory consistency by issuing a cache flush/sync when > + consistency is needed. If this flag is set V4L2 will attempt to > + allocate the buffer in non-consistent memory. The flag takes effect > + only if the buffer is used for :ref:`memory mapping <mmap>` I/O and the > + queue reports the :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability. > > .. c:type:: v4l2_memory > > diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > index d0c643db477a..21ecacc72487 100644 > --- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > +++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst > @@ -156,6 +156,13 @@ aborting or finishing any DMA in progress, an implicit > - Only valid for stateless decoders. If set, then userspace can set the > ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` flag to hold off on returning the > capture buffer until the OUTPUT timestamp changes. > + * - ``V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS`` > + - 0x00000040 > + - Set when the queue/buffer supports memory consistency and cache > + management hints. See :ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT`, > + :ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE` and > + :ref:`V4L2_BUF_FLAG_NO_CACHE_CLEAN`. > + > > Return Value > ============ > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c > index 2a604bd7793a..c847bcea6e95 100644 > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c > @@ -711,6 +711,8 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps) > *caps |= V4L2_BUF_CAP_SUPPORTS_DMABUF; > if (q->subsystem_flags & VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF) > *caps |= V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF; > + if (q->allow_cache_hints && (q->io_modes & VB2_MMAP)) > + *caps |= V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS; > #ifdef CONFIG_MEDIA_CONTROLLER_REQUEST_API > if (q->supports_requests) > *caps |= V4L2_BUF_CAP_SUPPORTS_REQUESTS; > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 5f9357dcb060..e92c29864730 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 { > /* > @@ -946,6 +948,7 @@ struct v4l2_requestbuffers { > #define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3) > #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4) > #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF (1 << 5) > +#define V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS (1 << 6) > > /** > * struct v4l2_plane - plane info for multi-planar buffers >
On (20/03/06 14:58), Hans Verkuil wrote: > > Please fold that in this patch. > Thanks! -ss
diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst index 3112300c2fa0..8084e3f2a58d 100644 --- a/Documentation/media/uapi/v4l/buffer.rst +++ b/Documentation/media/uapi/v4l/buffer.rst @@ -681,6 +681,35 @@ Buffer Flags \normalsize +.. _memory-flags: + +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 + - A buffer is allocated either in consistent (it will be automatically + coherent between the CPU and the bus) or non-consistent memory. The + latter can provide performance gains, for instance the CPU cache + sync/flush operations can be avoided if the buffer is accessed by the + corresponding device only and the CPU does not read/write to/from that + buffer. However, this requires extra care from the driver -- it must + guarantee memory consistency by issuing a cache flush/sync when + consistency is needed. If this flag is set V4L2 will attempt to + allocate the buffer in non-consistent memory. The flag takes effect + only if the buffer is used for :ref:`memory mapping <mmap>` I/O and the + queue reports the :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability. .. c:type:: v4l2_memory diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst index d0c643db477a..21ecacc72487 100644 --- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst +++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst @@ -156,6 +156,13 @@ aborting or finishing any DMA in progress, an implicit - Only valid for stateless decoders. If set, then userspace can set the ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` flag to hold off on returning the capture buffer until the OUTPUT timestamp changes. + * - ``V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS`` + - 0x00000040 + - Set when the queue/buffer supports memory consistency and cache + management hints. See :ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT`, + :ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE` and + :ref:`V4L2_BUF_FLAG_NO_CACHE_CLEAN`. + Return Value ============ diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c index 2a604bd7793a..c847bcea6e95 100644 --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c @@ -711,6 +711,8 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps) *caps |= V4L2_BUF_CAP_SUPPORTS_DMABUF; if (q->subsystem_flags & VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF) *caps |= V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF; + if (q->allow_cache_hints && (q->io_modes & VB2_MMAP)) + *caps |= V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS; #ifdef CONFIG_MEDIA_CONTROLLER_REQUEST_API if (q->supports_requests) *caps |= V4L2_BUF_CAP_SUPPORTS_REQUESTS; diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 5f9357dcb060..e92c29864730 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 { /* @@ -946,6 +948,7 @@ struct v4l2_requestbuffers { #define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3) #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4) #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF (1 << 5) +#define V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS (1 << 6) /** * struct v4l2_plane - plane info for multi-planar buffers
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 thus user-space is able to request vb2 buffer's memory to be either consistent (coherent) or non-consistent. The patch set also adds a corresponding capability flag: fill_buf_caps() reports V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS when queue supports user-space cache management hints. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> --- Documentation/media/uapi/v4l/buffer.rst | 29 +++++++++++++++++++ .../media/uapi/v4l/vidioc-reqbufs.rst | 7 +++++ .../media/common/videobuf2/videobuf2-v4l2.c | 2 ++ include/uapi/linux/videodev2.h | 3 ++ 4 files changed, 41 insertions(+)