On Tue October 2 2012 16:27:29 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@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> ---
> drivers/media/video/v4l2-compat-ioctl32.c | 1 +
> drivers/media/video/v4l2-dev.c | 1 +
> drivers/media/video/v4l2-ioctl.c | 10 ++++++++++
> include/linux/videodev2.h | 28 ++++++++++++++++++++++++++++
> include/media/v4l2-ioctl.h | 2 ++
> 5 files changed, 42 insertions(+)
>
> diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
> index f0b5aba..8788000 100644
> --- a/drivers/media/video/v4l2-compat-ioctl32.c
> +++ b/drivers/media/video/v4l2-compat-ioctl32.c
> @@ -971,6 +971,7 @@ 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 07aeafc..c43127c 100644
> --- a/drivers/media/video/v4l2-dev.c
> +++ b/drivers/media/video/v4l2-dev.c
> @@ -638,6 +638,7 @@ 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 dffd3c9..f3ec8c0 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -458,6 +458,15 @@ static void v4l_print_buffer(const void *arg, bool write_only)
> tc->type, tc->flags, tc->frames, *(__u32 *)tc->userbits);
> }
>
> +static void v4l_print_exportbuffer(const void *arg, bool write_only)
> +{
> + const struct v4l2_exportbuffer *p = arg;
> +
> + pr_cont("fd=%d, type=%s, index=%u, plane=%u, flags=0x%08x\n",
> + p->fd, prt_names(p->type, v4l2_type_names),
> + p->index, p->plane, p->flags);
> +}
> +
> static void v4l_print_create_buffers(const void *arg, bool write_only)
> {
> const struct v4l2_create_buffers *p = arg;
> @@ -1947,6 +1956,7 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
> IOCTL_INFO_STD(VIDIOC_S_FBUF, vidioc_s_fbuf, v4l_print_framebuffer, INFO_FL_PRIO),
> IOCTL_INFO_STD(VIDIOC_OVERLAY, vidioc_overlay, v4l_print_u32, INFO_FL_PRIO),
> IOCTL_INFO_FNC(VIDIOC_QBUF, v4l_qbuf, v4l_print_buffer, INFO_FL_QUEUE),
> + IOCTL_INFO_STD(VIDIOC_EXPBUF, vidioc_expbuf, v4l_print_exportbuffer, 0),
This needs the INFO_FL_QUEUE flag, that way this call is serialized
with the other queuing ioctls.
You can also add INFO_FL_CLEAR(v4l2_expbuf, flags). This assumes a field order
in the struct as given in my comment below. The FL_CLEAR flag will zero all
fields after 'flags'.
> IOCTL_INFO_FNC(VIDIOC_DQBUF, v4l_dqbuf, v4l_print_buffer, INFO_FL_QUEUE),
> IOCTL_INFO_FNC(VIDIOC_STREAMON, v4l_streamon, v4l_print_buftype, INFO_FL_PRIO | INFO_FL_QUEUE),
> IOCTL_INFO_FNC(VIDIOC_STREAMOFF, v4l_streamoff, v4l_print_buftype, INFO_FL_PRIO | INFO_FL_QUEUE),
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index e04a73e..f429b6a 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -688,6 +688,33 @@ 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)
> + * @flags: flags for newly created file, currently only O_CLOEXEC is
> + * supported, refer to manual of open syscall for more details
> + * @index: id number of the buffer
> + * @type: enum v4l2_buf_type; buffer type (type == *_MPLANE for
> + * multiplanar buffers);
> + * @plane: index of the plane to be exported, 0 for single plane queues
> + *
> + * 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 {
> + __s32 fd;
> + __u32 flags;
> + __u32 type; /* enum v4l2_buf_type */
> + __u32 index;
> + __u32 plane;
As suggested in my comments in the previous patch, I think it is a more natural
order to have the type/index/plane fields first in this struct.
Actually, I think that flags should also come before fd:
struct v4l2_exportbuffer {
__u32 type; /* enum v4l2_buf_type */
__u32 index;
__u32 plane;
__u32 flags;
__s32 fd;
__u32 reserved[11];
};
> + __u32 reserved[11];
> +};
> +
> /*
> * O V E R L A Y P R E V I E W
> */
> @@ -2558,6 +2585,7 @@ 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 e614c9c..38fb139 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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