On Tue, Nov 18, 2014 at 9:50 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> Document that drivers can access/modify the buffer contents in buf_prepare
> and buf_finish. That was not clearly stated before.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> include/media/videobuf2-core.h | 32 +++++++++++++++++---------------
> 1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index 6ef2d01..70ace7c 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -270,22 +270,24 @@ struct vb2_buffer {
> * queue setup from completing successfully; optional.
> * @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; 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.
> + * perform any initialization required before each
> + * hardware operation in this callback; drivers can
> + * access/modify the buffer here as it is still synced for
> + * the CPU; 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. The
> - * buffer state can be one of the following: DONE and
> - * ERROR occur while streaming is in progress, and the
> - * PREPARED state occurs when the queue has been canceled
> - * and all pending buffers are being returned to their
> - * default DEQUEUED state. Typically you only have to do
> - * something if the state is VB2_BUF_STATE_DONE, since in
> - * all other cases the buffer contents will be ignored
> - * anyway.
> + * userspace; the buffer is synced for the CPU, so drivers
> + * can access/modify the buffer contents; drivers may
> + * perform any operations required before userspace
> + * accesses the buffer; optional. The buffer state can be
> + * one of the following: DONE and ERROR occur while
> + * streaming is in progress, and the PREPARED state occurs
> + * when the queue has been canceled and all pending
> + * buffers are being returned to their default DEQUEUED
> + * state. Typically you only have to do something if the
> + * state is VB2_BUF_STATE_DONE, since in all other cases
> + * the buffer contents will be ignored anyway.
> * @buf_cleanup: called once before the buffer is freed; drivers may
> * perform any additional cleanup; optional.
> * @start_streaming: called once to enter 'streaming' state; the driver may
> --
> 2.1.1
>
--
Best regards,
Pawel Osciak
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