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Commit 5548a382 authored by Laurent Pinchart's avatar Laurent Pinchart Committed by Mauro Carvalho Chehab
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[media] media: vb2: Clarify queue_setup() and buf_prepare() usage documentation 



Explain how the two operations must handle formats and validate buffer
sizes when used with VIDIOC_CREATE_BUFS.

Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent c09aada7

include/media/videobuf2-core.h

+7 −4
Original line number Diff line number Diff line
@@ -219,8 +219,9 @@ struct vb2_buffer { 
 *			configured format and *num_buffers is the total number

 *			of buffers, that are being allocated. When called from

 *			VIDIOC_CREATE_BUFS, fmt != NULL and it describes the

 *			target frame format. In this case *num_buffers are being

 *			allocated additionally to q->num_buffers.

 *			target frame format (if the format isn't valid the

 *			callback must return -EINVAL). In this case *num_buffers

 *			are being allocated additionally to q->num_buffers.

 * @wait_prepare:	release any locks taken while calling vb2 functions;

 *			it is called before an ioctl needs to wait for a new

 *			buffer to arrive; required to avoid a deadlock in
@@ -236,8 +237,10 @@ struct vb2_buffer { 
 * @buf_prepare:	called every time the buffer is queued from userspace

 *			and from the VIDIOC_PREPARE_BUF ioctl; drivers may

 *			perform any initialization required before each hardware

 *			operation in this callback; if an error is returned, the

 *			buffer will not be queued in driver; optional

 *			operation in this callback; drivers that support

 *			VIDIOC_CREATE_BUFS must also validate the buffer size;

 *			if an error is returned, the buffer will not be queued

 *			in driver; optional

 * @buf_finish:		called before every dequeue of the buffer back to

 *			userspace; drivers may perform any operations required

 *			before userspace accesses the buffer; optional