[PATCHv2 3/9] v4l: add buffer exporting via dmabuf
Hans Verkuil
hverkuil at xs4all.nl
Mon Jul 30 23:33:56 PDT 2012
On Thu June 14 2012 16:32:23 Tomasz Stanislawski wrote:
> This patch adds extension to V4L2 api. It allow to export a mmap buffer as file
> descriptor. New ioctl VIDIOC_EXPBUF is added. It takes a buffer offset used by
> mmap and return a file descriptor on success.
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> ---
> drivers/media/video/v4l2-compat-ioctl32.c | 1 +
> drivers/media/video/v4l2-dev.c | 1 +
> drivers/media/video/v4l2-ioctl.c | 6 ++++++
> include/linux/videodev2.h | 26 ++++++++++++++++++++++++++
> include/media/v4l2-ioctl.h | 2 ++
> 5 files changed, 36 insertions(+)
>
> diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
> index d33ab18..141e745 100644
> --- a/drivers/media/video/v4l2-compat-ioctl32.c
> +++ b/drivers/media/video/v4l2-compat-ioctl32.c
> @@ -970,6 +970,7 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg)
> case VIDIOC_S_FBUF32:
> case VIDIOC_OVERLAY32:
> case VIDIOC_QBUF32:
> + case VIDIOC_EXPBUF:
> case VIDIOC_DQBUF32:
> case VIDIOC_STREAMON32:
> case VIDIOC_STREAMOFF32:
> diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
> index 5ccbd46..6bf6307 100644
> --- a/drivers/media/video/v4l2-dev.c
> +++ b/drivers/media/video/v4l2-dev.c
> @@ -597,6 +597,7 @@ static void determine_valid_ioctls(struct video_device *vdev)
> SET_VALID_IOCTL(ops, VIDIOC_REQBUFS, vidioc_reqbufs);
> SET_VALID_IOCTL(ops, VIDIOC_QUERYBUF, vidioc_querybuf);
> SET_VALID_IOCTL(ops, VIDIOC_QBUF, vidioc_qbuf);
> + SET_VALID_IOCTL(ops, VIDIOC_EXPBUF, vidioc_expbuf);
> SET_VALID_IOCTL(ops, VIDIOC_DQBUF, vidioc_dqbuf);
> SET_VALID_IOCTL(ops, VIDIOC_OVERLAY, vidioc_overlay);
> SET_VALID_IOCTL(ops, VIDIOC_G_FBUF, vidioc_g_fbuf);
> diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
> index 31fc2ad..a73b14e 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -212,6 +212,7 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
> IOCTL_INFO(VIDIOC_S_FBUF, INFO_FL_PRIO),
> IOCTL_INFO(VIDIOC_OVERLAY, INFO_FL_PRIO),
> IOCTL_INFO(VIDIOC_QBUF, 0),
> + IOCTL_INFO(VIDIOC_EXPBUF, 0),
> IOCTL_INFO(VIDIOC_DQBUF, 0),
> IOCTL_INFO(VIDIOC_STREAMON, INFO_FL_PRIO),
> IOCTL_INFO(VIDIOC_STREAMOFF, INFO_FL_PRIO),
> @@ -957,6 +958,11 @@ static long __video_do_ioctl(struct file *file,
> dbgbuf(cmd, vfd, p);
> break;
> }
> + case VIDIOC_EXPBUF:
> + {
> + ret = ops->vidioc_expbuf(file, fh, arg);
> + break;
> + }
> case VIDIOC_DQBUF:
> {
> struct v4l2_buffer *p = arg;
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 51b20f4..e8893a5 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -684,6 +684,31 @@ struct v4l2_buffer {
> #define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE 0x0800
> #define V4L2_BUF_FLAG_NO_CACHE_CLEAN 0x1000
>
> +/**
> + * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
> + *
> + * @fd: file descriptor associated with DMABUF (set by driver)
> + * @mem_offset: buffer memory offset as returned by VIDIOC_QUERYBUF in struct
> + * v4l2_buffer::m.offset (for single-plane formats) or
> + * v4l2_plane::m.offset (for multi-planar formats)
> + * @flags: flags for newly created file, currently only O_CLOEXEC is
> + * supported, refer to manual of open syscall for more details
> + *
> + * Contains data used for exporting a video buffer as DMABUF file descriptor.
> + * The buffer is identified by a 'cookie' returned by VIDIOC_QUERYBUF
> + * (identical to the cookie used to mmap() the buffer to userspace). All
> + * reserved fields must be set to zero. The field reserved0 is expected to
> + * become a structure 'type' allowing an alternative layout of the structure
> + * content. Therefore this field should not be used for any other extensions.
> + */
> +struct v4l2_exportbuffer {
> + __u32 fd;
> + __u32 reserved0;
> + __u32 mem_offset;
This should be a union identical to the m union in v4l2_plane, together with a
u32 memory field. That way you can just copy memory and m from v4l2_plane/buffer
and call expbuf. If new memory types are added in the future, then you don't need
to change this struct.
For that matter, wouldn't it be useful to support exporting a userptr buffer at
some point in the future?
BTW, this patch series needs to be rebased to the latest for_v3.6. Quite a few
core things have changed when it comes to adding new ioctls.
Regards,
Hans
> + __u32 flags;
> + __u32 reserved[12];
> +};
> +
> /*
> * O V E R L A Y P R E V I E W
> */
> @@ -2553,6 +2578,7 @@ struct v4l2_create_buffers {
> #define VIDIOC_S_FBUF _IOW('V', 11, struct v4l2_framebuffer)
> #define VIDIOC_OVERLAY _IOW('V', 14, int)
> #define VIDIOC_QBUF _IOWR('V', 15, struct v4l2_buffer)
> +#define VIDIOC_EXPBUF _IOWR('V', 16, struct v4l2_exportbuffer)
> #define VIDIOC_DQBUF _IOWR('V', 17, struct v4l2_buffer)
> #define VIDIOC_STREAMON _IOW('V', 18, int)
> #define VIDIOC_STREAMOFF _IOW('V', 19, int)
> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> index d8b76f7..ccd1faa 100644
> --- a/include/media/v4l2-ioctl.h
> +++ b/include/media/v4l2-ioctl.h
> @@ -119,6 +119,8 @@ struct v4l2_ioctl_ops {
> int (*vidioc_reqbufs) (struct file *file, void *fh, struct v4l2_requestbuffers *b);
> int (*vidioc_querybuf)(struct file *file, void *fh, struct v4l2_buffer *b);
> int (*vidioc_qbuf) (struct file *file, void *fh, struct v4l2_buffer *b);
> + int (*vidioc_expbuf) (struct file *file, void *fh,
> + struct v4l2_exportbuffer *e);
> int (*vidioc_dqbuf) (struct file *file, void *fh, struct v4l2_buffer *b);
>
> int (*vidioc_create_bufs)(struct file *file, void *fh, struct v4l2_create_buffers *b);
>
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