Hello Thomasz,
Instead of adding another IOCTL to query the file-descriptor in
user-space, why dont we extend the existing ones in v4l2/vb2?
When the memory type set is V4L2_MEMORY_DMABUF, call to VIDIOC_REQBUFS
/VIDIOC_QUERYBUF from driver can take/return the fd. We will need to add
another attribute to struct v4l2_requestbuffers for this.
struct v4l2_requestbuffers {
...
__u32 buf_fd;
};
The application requesting buffer would set it to -1, and will receive
the fd's when it calls the vb2_querybuf. In the same way, application
which is trying to attach to already allocated buffer will set this to
valid fd when it calls vidioc_reqbuf, and in vb2_reqbuf depending on the
memory type, this can be checked and used to attach with the dma_buf for
the respective buffer.
Ofcourse, this requires changes in vb2_reqbufs and vb2_querybuf similar
to what you did in vb2_expbufs.
Will there be any issues in such an approach?
Regards,
Subash
On 01/23/2012 07:21 PM, 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.stanisl...@samsung.com>
Signed-off-by: Kyungmin Park<kyungmin.p...@samsung.com>
---
drivers/media/video/v4l2-compat-ioctl32.c | 1 +
drivers/media/video/v4l2-ioctl.c | 11 +++++++++++
include/linux/videodev2.h | 1 +
include/media/v4l2-ioctl.h | 1 +
4 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/drivers/media/video/v4l2-compat-ioctl32.c
b/drivers/media/video/v4l2-compat-ioctl32.c
index c68531b..0f18b5e 100644
--- a/drivers/media/video/v4l2-compat-ioctl32.c
+++ b/drivers/media/video/v4l2-compat-ioctl32.c
@@ -954,6 +954,7 @@ 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-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index e1da8fc..cb29e00 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -207,6 +207,7 @@ static const char *v4l2_ioctls[] = {
[_IOC_NR(VIDIOC_S_FBUF)] = "VIDIOC_S_FBUF",
[_IOC_NR(VIDIOC_OVERLAY)] = "VIDIOC_OVERLAY",
[_IOC_NR(VIDIOC_QBUF)] = "VIDIOC_QBUF",
+ [_IOC_NR(VIDIOC_EXPBUF)] = "VIDIOC_EXPBUF",
[_IOC_NR(VIDIOC_DQBUF)] = "VIDIOC_DQBUF",
[_IOC_NR(VIDIOC_STREAMON)] = "VIDIOC_STREAMON",
[_IOC_NR(VIDIOC_STREAMOFF)] = "VIDIOC_STREAMOFF",
@@ -932,6 +933,16 @@ static long __video_do_ioctl(struct file *file,
dbgbuf(cmd, vfd, p);
break;
}
+ case VIDIOC_EXPBUF:
+ {
+ unsigned int *p = arg;
+
+ if (!ops->vidioc_expbuf)
+ break;
+
+ ret = ops->vidioc_expbuf(file, fh, *p);
+ break;
+ }
case VIDIOC_DQBUF:
{
struct v4l2_buffer *p = arg;
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 3c0ade1..448fbed 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -2183,6 +2183,7 @@ 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, __u32)
#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 4d1c74a..8201546 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -120,6 +120,7 @@ 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, __u32 offset);
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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