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authorTomi Valkeinen <tomi.valkeinen@ideasonboard.com>2021-04-12 13:02:09 +0200
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2021-06-08 12:04:08 +0200
commita810ed0b3370e0b3f448233d526d085effd1f829 (patch)
tree2a78bd9d06cc2ba2a6e7186c2574e8aff5a4b02e /include
parent5b448065febe1c6bb6693735844f2fb2b7b654dc (diff)
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 <tomi.valkeinen@ideasonboard.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/media/videobuf2-v4l2.h16
1 files changed, 16 insertions, 0 deletions
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
@@ -262,6 +262,22 @@ 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.
* @file: file argument passed to the poll file operation handler

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