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    Subject[PATCHv3 7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag
    Date
    This patch lets user-space to request a non-coherent 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.

    = CREATE_BUFS32

    struct v4l2_create_buffers32 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 byte of a 4 byte ->reserved[1] member of struct
    v4l2_requestbuffers. The struct, thus, now has reserved 3 bytes.

    Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
    ---
    .../media/v4l/vidioc-create-bufs.rst | 7 ++++-
    .../media/v4l/vidioc-reqbufs.rst | 11 ++++---
    .../media/common/videobuf2/videobuf2-core.c | 4 +--
    .../media/common/videobuf2/videobuf2-v4l2.c | 31 +++++++++++++++++--
    drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 9 +++++-
    drivers/media/v4l2-core/v4l2-ioctl.c | 4 +--
    include/uapi/linux/videodev2.h | 9 ++++--
    7 files changed, 60 insertions(+), 15 deletions(-)

    diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
    index f98f18c9e91c..a048a9f6b7b6 100644
    --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
    +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst
    @@ -113,7 +113,12 @@ than the number requested.
    ``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/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
    index e59306aba2b0..099fa6695167 100644
    --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
    +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
    @@ -104,10 +104,13 @@ 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
    - - ``reserved``\ [1]
    - - A place holder for future extensions. Drivers and applications
    - must set the array to zero.
    + * - __u8
    + - ``flags``
    + - Specifies additional buffer management attributes.
    + See :ref:`memory-flags`.
    + * - __u8
    + - ``reserved``\ [3]
    + - Reserved for future extensions.

    .. _v4l2-buf-capabilities:
    .. _V4L2-BUF-CAP-SUPPORTS-MMAP:
    diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
    index af4db310cf5e..38505783247e 100644
    --- a/drivers/media/common/videobuf2/videobuf2-core.c
    +++ b/drivers/media/common/videobuf2/videobuf2-core.c
    @@ -762,7 +762,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
    {
    unsigned int num_buffers, allocated_buffers, num_planes = 0;
    unsigned plane_sizes[VB2_MAX_PLANES] = { };
    - bool coherent_mem = true;
    + bool coherent_mem = !(flags & V4L2_MEMORY_FLAG_NON_COHERENT);
    unsigned int i;
    int ret;

    @@ -906,7 +906,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
    {
    unsigned int num_planes = 0, num_buffers, allocated_buffers;
    unsigned plane_sizes[VB2_MAX_PLANES] = { };
    - bool coherent_mem = true;
    + bool coherent_mem = !(flags & V4L2_MEMORY_FLAG_NON_COHERENT);
    int ret;

    if (q->num_buffers == VB2_MAX_FRAME) {
    diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
    index b4f70ddb09b0..6edf4508c636 100644
    --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
    +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
    @@ -692,12 +692,32 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
    #endif
    }

    +static void validate_memory_flags(struct vb2_queue *q,
    + int memory,
    + u32 *flags)
    +{
    + if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
    + /*
    + * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
    + * but in order to avoid bugs we zero out all bits.
    + */
    + *flags = 0;
    + } else {
    + /* Clear all unknown flags. */
    + *flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
    + }
    +}
    +
    int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
    {
    int ret = vb2_verify_memory_type(q, req->memory, req->type);
    + u32 flags = req->flags;

    fill_buf_caps(q, &req->capabilities);
    - return ret ? ret : vb2_core_reqbufs(q, req->memory, 0, &req->count);
    + validate_memory_flags(q, req->memory, &flags);
    + req->flags = flags;
    + return ret ? ret : vb2_core_reqbufs(q, req->memory,
    + req->flags, &req->count);
    }
    EXPORT_SYMBOL_GPL(vb2_reqbufs);

    @@ -729,6 +749,7 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
    unsigned i;

    fill_buf_caps(q, &create->capabilities);
    + validate_memory_flags(q, create->memory, &create->flags);
    create->index = q->num_buffers;
    if (create->count == 0)
    return ret != -EBUSY ? ret : 0;
    @@ -772,7 +793,7 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
    if (requested_sizes[i] == 0)
    return -EINVAL;
    return ret ? ret : vb2_core_create_bufs(q, create->memory,
    - 0,
    + create->flags,
    &create->count,
    requested_planes,
    requested_sizes);
    @@ -969,13 +990,16 @@ 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);
    + u32 flags = p->flags;

    fill_buf_caps(vdev->queue, &p->capabilities);
    + validate_memory_flags(vdev->queue, p->memory, &flags);
    + p->flags = flags;
    if (res)
    return res;
    if (vb2_queue_is_busy(vdev, file))
    return -EBUSY;
    - res = vb2_core_reqbufs(vdev->queue, p->memory, 0, &p->count);
    + res = vb2_core_reqbufs(vdev->queue, p->memory, p->flags, &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)
    @@ -993,6 +1017,7 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,

    p->index = vdev->queue->num_buffers;
    fill_buf_caps(vdev->queue, &p->capabilities);
    + validate_memory_flags(vdev->queue, p->memory, &p->flags);
    /*
    * If count == 0, then just check if memory and type are valid.
    * Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
    diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
    index 47aff3b19742..8176769a89fa 100644
    --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
    +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
    @@ -126,6 +126,9 @@ struct v4l2_format32 {
    * @memory: buffer memory type
    * @format: frame format, for which buffers are requested
    * @capabilities: capabilities of this buffer type.
    + * @flags: additional buffer management attributes (ignored unless the
    + * queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability and
    + * configured for MMAP streaming I/O).
    * @reserved: future extensions
    */
    struct v4l2_create_buffers32 {
    @@ -134,7 +137,8 @@ struct v4l2_create_buffers32 {
    __u32 memory; /* enum v4l2_memory */
    struct v4l2_format32 format;
    __u32 capabilities;
    - __u32 reserved[7];
    + __u32 flags;
    + __u32 reserved[6];
    };

    static int get_v4l2_format32(struct v4l2_format *p64,
    @@ -182,6 +186,8 @@ static int get_v4l2_create32(struct v4l2_create_buffers *p64,
    if (copy_from_user(p64, p32,
    offsetof(struct v4l2_create_buffers32, format)))
    return -EFAULT;
    + if (copy_from_user(&p64->flags, &p32->flags, sizeof(p32->flags)))
    + return -EFAULT;
    return get_v4l2_format32(&p64->format, &p32->format);
    }

    @@ -227,6 +233,7 @@ static int put_v4l2_create32(struct v4l2_create_buffers *p64,
    if (copy_to_user(p32, p64,
    offsetof(struct v4l2_create_buffers32, format)) ||
    put_user(p64->capabilities, &p32->capabilities) ||
    + put_user(p64->flags, &p32->flags) ||
    copy_to_user(p32->reserved, p64->reserved, sizeof(p64->reserved)))
    return -EFAULT;
    return put_v4l2_format32(&p64->format, &p32->format);
    diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
    index 05d5db3d85e5..6a941da33998 100644
    --- a/drivers/media/v4l2-core/v4l2-ioctl.c
    +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
    @@ -2004,7 +2004,7 @@ static int v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
    if (ret)
    return ret;

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

    return ops->vidioc_reqbufs(file, fh, p);
    }
    @@ -2045,7 +2045,7 @@ 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 9d11e1d9c934..7973aa0465d2 100644
    --- a/include/uapi/linux/videodev2.h
    +++ b/include/uapi/linux/videodev2.h
    @@ -953,7 +953,8 @@ struct v4l2_requestbuffers {
    __u32 type; /* enum v4l2_buf_type */
    __u32 memory; /* enum v4l2_memory */
    __u32 capabilities;
    - __u32 reserved[1];
    + __u8 flags;
    + __u8 reserved[3];
    };

    #define V4L2_MEMORY_FLAG_NON_COHERENT (1 << 0)
    @@ -2501,6 +2502,9 @@ struct v4l2_dbg_chip_info {
    * @memory: enum v4l2_memory; buffer memory type
    * @format: frame format, for which buffers are requested
    * @capabilities: capabilities of this buffer type.
    + * @flags: additional buffer management attributes (ignored unless the
    + * queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability
    + * and configured for MMAP streaming I/O).
    * @reserved: future extensions
    */
    struct v4l2_create_buffers {
    @@ -2509,7 +2513,8 @@ struct v4l2_create_buffers {
    __u32 memory;
    struct v4l2_format format;
    __u32 capabilities;
    - __u32 reserved[7];
    + __u32 flags;
    + __u32 reserved[6];
    };

    /*
    --
    2.32.0.93.g670b81a890-goog
    \
     
     \ /
      Last update: 2021-07-09 11:21    [W:5.537 / U:0.020 seconds]
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