Commit a810ed0b authored by Tomi Valkeinen's avatar Tomi Valkeinen Committed by Mauro Carvalho Chehab
Browse files

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: default avatarTomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent 5b448065

drivers/media/common/videobuf2/videobuf2-v4l2.c

+14 −0
Original line number Diff line number Diff line
@@ -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);

include/media/videobuf2-v4l2.h

+16 −0
Original line number Diff line number Diff line
@@ -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.