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Subject[PATCHv4 05/11] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag
Date
This patch lets user-space to request a non-consistent memory
allocation during CREATE_BUFS and REQBUFS ioctl calls.

= CREATE_BUFS

struct v4l2_create_buffers has seven 4-byte reserved areas,
so reserved[0] is renamed to ->flags. The struct, thus, now
has six reserved 4-byte regions.

= REQBUFS

We use one bit of a ->reserved[1] member of struct v4l2_requestbuffers,
which is now renamed to ->flags. Unlike v4l2_create_buffers, struct
v4l2_requestbuffers does not have enough reserved room. Therefore for
backward compatibility ->reserved and ->flags were put into anonymous
union.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
.../media/uapi/v4l/vidioc-create-bufs.rst | 7 ++++-
.../media/uapi/v4l/vidioc-reqbufs.rst | 11 +++++--
.../media/common/videobuf2/videobuf2-v4l2.c | 31 +++++++++++++++++--
drivers/media/v4l2-core/v4l2-ioctl.c | 5 +--
include/uapi/linux/videodev2.h | 8 +++--
5 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
index bd08e4f77ae4..a9c6c89f5098 100644
--- a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
@@ -121,7 +121,12 @@ than the number requested.
other changes, then set ``count`` to 0, ``memory`` to
``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type.
* - __u32
- - ``reserved``\ [7]
+ - ``flags``
+ - Specifies additional buffer management attributes.
+ See :ref:`memory-flags`.
+
+ * - __u32
+ - ``reserved``\ [6]
- A place holder for future extensions. Drivers and applications
must set the array to zero.

diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
index 21ecacc72487..faf0df4f9bb6 100644
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -112,10 +112,17 @@ 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]
- - A place holder for future extensions. Drivers and applications
- must set the array to zero.
+ - Kept for backwards compatibility. Use ``flags`` instead.
+ * - }
+ -

.. tabularcolumns:: |p{6.1cm}|p{2.2cm}|p{8.7cm}|

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 6111d74f68c9..b4b379f3bf98 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -722,9 +722,18 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
{
int ret = vb2_verify_memory_type(q, req->memory, req->type);
+ bool consistent = true;
+
+ if (!vb2_queue_allows_cache_hints(q))
+ req->flags &= ~V4L2_FLAG_MEMORY_NON_CONSISTENT;
+
+ if (req->flags & V4L2_FLAG_MEMORY_NON_CONSISTENT)
+ consistent = false;

fill_buf_caps(q, &req->capabilities);
- return ret ? ret : vb2_core_reqbufs(q, req->memory, true, &req->count);
+ if (ret)
+ return ret;
+ return vb2_core_reqbufs(q, req->memory, consistent, &req->count);
}
EXPORT_SYMBOL_GPL(vb2_reqbufs);

@@ -753,6 +762,7 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
unsigned requested_sizes[VIDEO_MAX_PLANES];
struct v4l2_format *f = &create->format;
int ret = vb2_verify_memory_type(q, create->memory, f->type);
+ bool consistent = true;
unsigned i;

fill_buf_caps(q, &create->capabilities);
@@ -798,7 +808,14 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
for (i = 0; i < requested_planes; i++)
if (requested_sizes[i] == 0)
return -EINVAL;
- return ret ? ret : vb2_core_create_bufs(q, create->memory, true,
+
+ if (!vb2_queue_allows_cache_hints(q))
+ create->flags &= ~V4L2_FLAG_MEMORY_NON_CONSISTENT;
+
+ if (create->flags & V4L2_FLAG_MEMORY_NON_CONSISTENT)
+ consistent = false;
+
+ return ret ? ret : vb2_core_create_bufs(q, create->memory, consistent,
&create->count, requested_planes, requested_sizes);
}
EXPORT_SYMBOL_GPL(vb2_create_bufs);
@@ -968,13 +985,21 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,
{
struct video_device *vdev = video_devdata(file);
int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);
+ bool consistent = true;

fill_buf_caps(vdev->queue, &p->capabilities);
if (res)
return res;
if (vb2_queue_is_busy(vdev, file))
return -EBUSY;
- res = vb2_core_reqbufs(vdev->queue, p->memory, true, &p->count);
+
+ if (!vb2_queue_allows_cache_hints(vdev->queue))
+ p->flags &= ~V4L2_FLAG_MEMORY_NON_CONSISTENT;
+
+ if (p->flags & V4L2_FLAG_MEMORY_NON_CONSISTENT)
+ consistent = false;
+
+ res = vb2_core_reqbufs(vdev->queue, p->memory, consistent, &p->count);
/* If count == 0, then the owner has released all buffers and he
is no longer owner of the queue. Otherwise we have a new owner. */
if (res == 0)
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index fbcc7a20eedf..53b87bfd50d7 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1973,9 +1973,6 @@ static int v4l_reqbufs(const struct v4l2_ioctl_ops *ops,

if (ret)
return ret;
-
- CLEAR_AFTER_FIELD(p, capabilities);
-
return ops->vidioc_reqbufs(file, fh, p);
}

@@ -2015,7 +2012,7 @@ static int v4l_create_bufs(const struct v4l2_ioctl_ops *ops,
if (ret)
return ret;

- CLEAR_AFTER_FIELD(create, capabilities);
+ CLEAR_AFTER_FIELD(create, flags);

v4l_sanitize_format(&create->format);

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index e92c29864730..12b1bd220347 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -938,7 +938,10 @@ struct v4l2_requestbuffers {
__u32 type; /* enum v4l2_buf_type */
__u32 memory; /* enum v4l2_memory */
__u32 capabilities;
- __u32 reserved[1];
+ union {
+ __u32 flags;
+ __u32 reserved[1];
+ };
};

/* capabilities for struct v4l2_requestbuffers and v4l2_create_buffers */
@@ -2446,7 +2449,8 @@ struct v4l2_create_buffers {
__u32 memory;
struct v4l2_format format;
__u32 capabilities;
- __u32 reserved[7];
+ __u32 flags;
+ __u32 reserved[6];
};

/*
--
2.25.0.265.gbab2e86ba0-goog
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