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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: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Laurent Pinchart 2013-08-01 21:44:38 -03:00 committed by Mauro Carvalho Chehab
parent c09aada7ac
commit 5548a38250
1 changed files with 7 additions and 4 deletions
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11
include/media/videobuf2-core.h
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@ -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