From a810ed0b3370e0b3f448233d526d085effd1f829 Mon Sep 17 00:00:00 2001 From: Tomi Valkeinen Date: Mon, 12 Apr 2021 13:02:09 +0200 Subject: media: videobuf2-v4l2.c: add vb2_queue_change_type() helper 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 Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- include/media/videobuf2-v4l2.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include/media/videobuf2-v4l2.h') diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h index c203047eb834..b66585e304e2 100644 --- a/include/media/videobuf2-v4l2.h +++ b/include/media/videobuf2-v4l2.h @@ -261,6 +261,22 @@ 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. + * @type: the type to change to (V4L2_BUF_TYPE_VIDEO_*) + * + * 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 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. -- cgit v1.2.3