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Subject[RFC][PATCHv2 05/12] 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.

Change-Id: I0eaab3428de499ce1bce6fc6b26c5ca5ff405882
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
.../media/uapi/v4l/vidioc-create-bufs.rst | 9 +++++++-
.../media/uapi/v4l/vidioc-reqbufs.rst | 15 ++++++++++---
.../media/common/videobuf2/videobuf2-v4l2.c | 21 ++++++++++++++++---
drivers/media/v4l2-core/v4l2-ioctl.c | 5 +----
include/uapi/linux/videodev2.h | 8 +++++--
5 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
index bd08e4f77ae4..68185e94b686 100644
--- a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
@@ -121,7 +121,14 @@ 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. Valid only when
+ queue reports :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability.
+ Old drivers and applications must set it to zero.
+
+
+ * - __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 d0c643db477a..9741dac0d5b3 100644
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -112,10 +112,19 @@ 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. Valid only when
+ queue reports :ref:`V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS` capability.
+ Old drivers and applications must set it to zero.
+
+ * -
+ - __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 7cdfcd1baf82..eb5d1306cb03 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -707,9 +707,15 @@ 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 (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);

@@ -738,6 +744,7 @@ 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);
@@ -783,7 +790,11 @@ 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 (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);
@@ -953,13 +964,17 @@ 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 (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 aaf83e254272..9791e2882382 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 72efc1c544cd..169a8cf345ed 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 */
@@ -2445,7 +2448,8 @@ struct v4l2_create_buffers {
__u32 memory;
struct v4l2_format format;
__u32 capabilities;
- __u32 reserved[7];
+ __u32 flags;
+ __u32 reserved[6];
};

/*
--
2.25.0.341.g760bfbb309-goog
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