Hi Hans,
On Tuesday 31 July 2012 08:33:56 Hans Verkuil wrote:
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@samsung.com Signed-off-by: Kyungmin Park kyungmin.park@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.
OK, reserved0 could be replace by __u32 memory. Could we have other dma-buf export types in the future not corresponding to a memory type ? I don't see any use case right now though.
For that matter, wouldn't it be useful to support exporting a userptr buffer at some point in the future?
Shouldn't USERPTR usage be discouraged once we get dma-buf support ?
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.