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media: vb2-core: document the REQUEUEING state 

VB2_BUF_STATE_REQUEUEING is accepted by vb2_buffer_done() but not
documented, so add it along with notes about calls in interrupt
context.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Pawel Osciak <pawel@osciak.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Luca Ceresoli 2018-03-08 07:26:21 -05:00 committed by Mauro Carvalho Chehab
parent 45ad39999b
commit 68a06bd04e
1 changed files with 15 additions and 9 deletions
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24
include/media/videobuf2-core.h
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@ -358,12 +358,12 @@ struct vb2_buffer {
* driver can return an error if hardware fails, in that
* case all buffers that have been already given by
* the @buf_queue callback are to be returned by the driver
* by calling vb2_buffer_done() with %VB2_BUF_STATE_QUEUED.
* If you need a minimum number of buffers before you can
* start streaming, then set
* &vb2_queue->min_buffers_needed. If that is non-zero then
* @start_streaming won't be called until at least that
* many buffers have been queued up by userspace.
* by calling vb2_buffer_done() with %VB2_BUF_STATE_QUEUED
* or %VB2_BUF_STATE_REQUEUEING. If you need a minimum
* number of buffers before you can start streaming, then
* set &vb2_queue->min_buffers_needed. If that is non-zero
* then @start_streaming won't be called until at least
* that many buffers have been queued up by userspace.
* @stop_streaming: called when 'streaming' state must be disabled; driver
* should stop any DMA transactions or wait until they
* finish and give back all buffers it got from &buf_queue
@ -601,8 +601,9 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
* @state: state of the buffer, as defined by &enum vb2_buffer_state.
* Either %VB2_BUF_STATE_DONE if the operation finished
* successfully, %VB2_BUF_STATE_ERROR if the operation finished
* with an error or %VB2_BUF_STATE_QUEUED if the driver wants to
* requeue buffers.
* with an error or any of %VB2_BUF_STATE_QUEUED or
* %VB2_BUF_STATE_REQUEUEING if the driver wants to
* requeue buffers (see below).
*
* This function should be called by the driver after a hardware operation on
* a buffer is finished and the buffer may be returned to userspace. The driver
@ -613,7 +614,12 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
* While streaming a buffer can only be returned in state DONE or ERROR.
* The &vb2_ops->start_streaming op can also return them in case the DMA engine
* cannot be started for some reason. In that case the buffers should be
* returned with state QUEUED to put them back into the queue.
* returned with state QUEUED or REQUEUEING to put them back into the queue.
*
* %VB2_BUF_STATE_REQUEUEING is like %VB2_BUF_STATE_QUEUED, but it also calls
* &vb2_ops->buf_queue to queue buffers back to the driver. Note that calling
* vb2_buffer_done(..., VB2_BUF_STATE_REQUEUEING) from interrupt context will
* result in &vb2_ops->buf_queue being called in interrupt context as well.
*/
void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);