| Message ID | 20210412081255.104788-1-tomi.valkeinen@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: videobuf2-v4l2.c: add vb2_queue_change_type() helper | expand |
Hi Tomi, On 12/04/2021 10:12, Tomi Valkeinen wrote: > On some platforms a video device can capture either video data or > metadata. The driver can implement vidioc functions for both video and > metadata, and use a single vb2_queue for the buffers. However, vb2_queue > requires choosing a single buffer type, which conflicts with the idea of > capturing either video or metadata. > > The buffer type of vb2_queue can be changed, but it's not obvious how > this should be done in the drivers. To help this, add a new helper > function vb2_queue_change_type() which ensures the correct checks and > documents how it can be used. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> > --- > drivers/media/common/videobuf2/videobuf2-v4l2.c | 14 ++++++++++++++ > include/media/videobuf2-v4l2.h | 15 +++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c > index 7e96f67c60ba..2988bb38ceb1 100644 > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c > @@ -939,6 +939,20 @@ void vb2_queue_release(struct vb2_queue *q) > } > EXPORT_SYMBOL_GPL(vb2_queue_release); > > +int vb2_queue_change_type(struct vb2_queue *q, unsigned int type) > +{ > + if (type == q->type) > + return 0; > + > + if (vb2_is_busy(q)) > + return -EBUSY; > + > + q->type = type; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(vb2_queue_change_type); > + > __poll_t vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) > { > struct video_device *vfd = video_devdata(file); > diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h > index c203047eb834..3e604c1b5e1b 100644 > --- a/include/media/videobuf2-v4l2.h > +++ b/include/media/videobuf2-v4l2.h > @@ -261,6 +261,21 @@ int __must_check vb2_queue_init_name(struct vb2_queue *q, const char *name); > */ > void vb2_queue_release(struct vb2_queue *q); > > +/** > + * vb2_queue_change_type() - change the type of an inactive vb2_queue > + * @q: pointer to &struct vb2_queue with videobuf2 queue. > + * > + * This function changes the type of the vb2_queue. This is only possible > + * if the queue is not busy (i.e. no buffers have been queued). queued -> allocated > + * > + * vb2_queue_change_type() can be used to support multiple buffer types using > + * the same queue. The driver can implement v4l2_ioctl_ops.vidioc_reqbufs and > + * v4l2_ioctl_ops.vidioc_create_bufs functions and call vb2_queue_change_type() > + * before calling vb2_ioctl_reqbufs() or vb2_ioctl_create_bufs(), and thus > + * "lock" the buffer type until the buffers have been released. > + */ > +int vb2_queue_change_type(struct vb2_queue *q, unsigned int type); > + > /** > * vb2_poll() - implements poll userspace operation > * @q: pointer to &struct vb2_queue with videobuf2 queue. > Can you also update vivid to use this function? That would also be a good test. Check with v4l2-compliance as well. It is not impossible that some changes have to be made to v4l2-compliance, ping me on irc if that's the case. Regards, Hans
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c index 7e96f67c60ba..2988bb38ceb1 100644 --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c @@ -939,6 +939,20 @@ void vb2_queue_release(struct vb2_queue *q) } EXPORT_SYMBOL_GPL(vb2_queue_release); +int vb2_queue_change_type(struct vb2_queue *q, unsigned int type) +{ + if (type == q->type) + return 0; + + if (vb2_is_busy(q)) + return -EBUSY; + + q->type = type; + + return 0; +} +EXPORT_SYMBOL_GPL(vb2_queue_change_type); + __poll_t vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) { struct video_device *vfd = video_devdata(file); diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h index c203047eb834..3e604c1b5e1b 100644 --- a/include/media/videobuf2-v4l2.h +++ b/include/media/videobuf2-v4l2.h @@ -261,6 +261,21 @@ int __must_check vb2_queue_init_name(struct vb2_queue *q, const char *name); */ void vb2_queue_release(struct vb2_queue *q); +/** + * vb2_queue_change_type() - change the type of an inactive vb2_queue + * @q: pointer to &struct vb2_queue with videobuf2 queue. + * + * This function changes the type of the vb2_queue. This is only possible + * if the queue is not busy (i.e. no buffers have been queued). + * + * vb2_queue_change_type() can be used to support multiple buffer types using + * the same queue. The driver can implement v4l2_ioctl_ops.vidioc_reqbufs and + * v4l2_ioctl_ops.vidioc_create_bufs functions and call vb2_queue_change_type() + * before calling vb2_ioctl_reqbufs() or vb2_ioctl_create_bufs(), and thus + * "lock" the buffer type until the buffers have been released. + */ +int vb2_queue_change_type(struct vb2_queue *q, unsigned int type); + /** * vb2_poll() - implements poll userspace operation * @q: pointer to &struct vb2_queue with videobuf2 queue.
On some platforms a video device can capture either video data or metadata. The driver can implement vidioc functions for both video and metadata, and use a single vb2_queue for the buffers. However, vb2_queue requires choosing a single buffer type, which conflicts with the idea of capturing either video or metadata. The buffer type of vb2_queue can be changed, but it's not obvious how this should be done in the drivers. To help this, add a new helper function vb2_queue_change_type() which ensures the correct checks and documents how it can be used. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> --- drivers/media/common/videobuf2/videobuf2-v4l2.c | 14 ++++++++++++++ include/media/videobuf2-v4l2.h | 15 +++++++++++++++ 2 files changed, 29 insertions(+)