The patch partially reverts some of the UAPI bits of the buffer
cache management hints. Namely, the queue consistency (memory
coherency) user-space hint because, as it turned out, the kernel
implementation of this feature was misusing DMA_ATTR_NON_CONSISTENT.
The patch revers both kernel and user space parts: removes the
DMA consistency attr functions, rollbacks changes to v4l2_requestbuffers,
v4l2_create_buffers structures and corresponding UAPI functions
(plus compat32 layer) and cleanups the documentation.
Signed-off-by: Christoph Hellwig
Signed-off-by: Sergey Senozhatsky
---
.../userspace-api/media/v4l/buffer.rst| 17 ---
.../media/v4l/vidioc-create-bufs.rst | 6 +--
.../media/v4l/vidioc-reqbufs.rst | 12 +
.../media/common/videobuf2/videobuf2-core.c | 46 +++
.../common/videobuf2/videobuf2-dma-contig.c | 19
.../media/common/videobuf2/videobuf2-dma-sg.c | 3 +-
.../media/common/videobuf2/videobuf2-v4l2.c | 18 +---
drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 10 +---
drivers/media/v4l2-core/v4l2-ioctl.c | 5 +-
include/media/videobuf2-core.h| 7 +--
include/uapi/linux/videodev2.h| 13 +-
11 files changed, 22 insertions(+), 134 deletions(-)
diff --git a/Documentation/userspace-api/media/v4l/buffer.rst
b/Documentation/userspace-api/media/v4l/buffer.rst
index 177ed8b6ce62..4f95496adc5b 100644
--- a/Documentation/userspace-api/media/v4l/buffer.rst
+++ b/Documentation/userspace-api/media/v4l/buffer.rst
@@ -694,23 +694,6 @@ Memory Consistency Flags
:stub-columns: 0
:widths: 3 1 4
-* .. _`V4L2-FLAG-MEMORY-NON-CONSISTENT`:
-
- - ``V4L2_FLAG_MEMORY_NON_CONSISTENT``
- - 0x0001
- - 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 ` I/O and the
- queue reports the :ref:`V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS
- ` capability.
-
.. c:type:: v4l2_memory
enum v4l2_memory
diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
index c050dffa4237..d999028f47df 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
@@ -113,13 +113,9 @@ than the number requested.
If you want to just query the capabilities without making any
other changes, then set ``count`` to 0, ``memory`` to
``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type.
-* - __u32
- - ``flags``
- - Specifies additional buffer management attributes.
- See :ref:`memory-flags`.
* - __u32
- - ``reserved``\ [6]
+ - ``reserved``\ [7]
- A place holder for future extensions. Drivers and applications
must set the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
index 47e433161690..afc35cd7b614 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
@@ -105,17 +105,10 @@ 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.
-* - union {
- - (anonymous)
-* - __u32
- - ``flags``
- - Specifies additional buffer management attributes.
- See :ref:`memory-flags`.
* - __u32
- ``reserved``\ [1]
- - Kept for backwards compatibility. Use ``flags`` instead.
-* - }
- -
+ - A place holder for future extensions. Drivers and applications
+ must set the array to zero.
.. tabularcolumns:: |p{6.1cm}|p{2.2cm}|p{8.7cm}|
@@ -162,7 +155,6 @@ aborting or finishing any DMA in progress, an implicit
- This capability is set by the driver to indicate that the queue
supports
cache and memory management hints. However, it's only valid when the
queue is used for :ref:`memory mapping ` streaming I/O. See
-:ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT
`,
:ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
` and
