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media: vb2: add (un)prepare_streaming queue ops

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When userspace called VIDIOC_STREAMON, then you want to claim any streaming
resources needed and validate the video pipeline. Waiting for
start_streaming to be called is too late, since that can be postponed
until the required minimum of buffers is queued.

So add a prepare_streaming op (optional) that can be used for that
purpose, and a matching unprepare_streaming op (optional) that can
release any claimed resources. The unprepare_streaming op is called
when VIDIOC_STREAMOFF is called and q->streaming is 1, or when the
filehandle is closed while q->streaming is 1.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Hans Verkuil 2022-06-22 10:31:44 +01:00 committed by Mauro Carvalho Chehab
parent e9305a003f
commit a10b215325
2 changed files with 35 additions and 4 deletions
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25
drivers/media/common/videobuf2/videobuf2-core.c
View File

@ -544,6 +544,7 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
*/
if (q->num_buffers) {
bool unbalanced = q->cnt_start_streaming != q->cnt_stop_streaming ||
q->cnt_prepare_streaming != q->cnt_unprepare_streaming ||
q->cnt_wait_prepare != q->cnt_wait_finish;
if (unbalanced || debug) {
@ -552,14 +553,18 @@ static int __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
pr_info(" setup: %u start_streaming: %u stop_streaming: %u\n",
q->cnt_queue_setup, q->cnt_start_streaming,
q->cnt_stop_streaming);
pr_info(" prepare_streaming: %u unprepare_streaming: %u\n",
q->cnt_prepare_streaming, q->cnt_unprepare_streaming);
pr_info(" wait_prepare: %u wait_finish: %u\n",
q->cnt_wait_prepare, q->cnt_wait_finish);
}
q->cnt_queue_setup = 0;
q->cnt_wait_prepare = 0;
q->cnt_wait_finish = 0;
q->cnt_prepare_streaming = 0;
q->cnt_start_streaming = 0;
q->cnt_stop_streaming = 0;
q->cnt_unprepare_streaming = 0;
}
for (buffer = 0; buffer < q->num_buffers; ++buffer) {
struct vb2_buffer *vb = q->bufs[buffer];
@ -1991,6 +1996,9 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
if (q->start_streaming_called)
call_void_qop(q, stop_streaming, q);
if (q->streaming)
call_void_qop(q, unprepare_streaming, q);
/*
* If you see this warning, then the driver isn't cleaning up properly
* in stop_streaming(). See the stop_streaming() documentation in
@ -2102,6 +2110,12 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
return -EINVAL;
}
ret = call_qop(q, prepare_streaming, q);
if (ret)
return ret;
q->streaming = 1;
/*
* Tell driver to start streaming provided sufficient buffers
* are available.
@ -2109,16 +2123,19 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
if (q->queued_count >= q->min_buffers_needed) {
ret = v4l_vb2q_enable_media_source(q);
if (ret)
return ret;
goto unprepare;
ret = vb2_start_streaming(q);
if (ret)
return ret;
goto unprepare;
}
q->streaming = 1;
dprintk(q, 3, "successful\n");
return 0;
unprepare:
call_void_qop(q, unprepare_streaming, q);
q->streaming = 0;
return ret;
}
EXPORT_SYMBOL_GPL(vb2_core_streamon);

14
include/media/videobuf2-core.h
View File

@ -386,6 +386,12 @@ struct vb2_buffer {
* the buffer contents will be ignored anyway.
* @buf_cleanup: called once before the buffer is freed; drivers may
* perform any additional cleanup; optional.
* @prepare_streaming: called once to prepare for 'streaming' state; this is
* where validation can be done to verify everything is
* okay and streaming resources can be claimed. It is
* called when the VIDIOC_STREAMON ioctl is called. The
* actual streaming starts when @start_streaming is called.
* Optional.
* @start_streaming: called once to enter 'streaming' state; the driver may
* receive buffers with @buf_queue callback
* before @start_streaming is called; the driver gets the
@ -405,6 +411,10 @@ struct vb2_buffer {
* callback by calling vb2_buffer_done() with either
* %VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use
* vb2_wait_for_all_buffers() function
* @unprepare_streaming:called as counterpart to @prepare_streaming; any claimed
* streaming resources can be released here. It is
* called when the VIDIOC_STREAMOFF ioctls is called or
* when the streaming filehandle is closed. Optional.
* @buf_queue: passes buffer vb to the driver; driver may start
* hardware operation on this buffer; driver should give
* the buffer back by calling vb2_buffer_done() function;
@ -432,8 +442,10 @@ struct vb2_ops {
void (*buf_finish)(struct vb2_buffer *vb);
void (*buf_cleanup)(struct vb2_buffer *vb);
int (*prepare_streaming)(struct vb2_queue *q);
int (*start_streaming)(struct vb2_queue *q, unsigned int count);
void (*stop_streaming)(struct vb2_queue *q);
void (*unprepare_streaming)(struct vb2_queue *q);
void (*buf_queue)(struct vb2_buffer *vb);
@ -641,8 +653,10 @@ struct vb2_queue {
u32 cnt_queue_setup;
u32 cnt_wait_prepare;
u32 cnt_wait_finish;
u32 cnt_prepare_streaming;
u32 cnt_start_streaming;
u32 cnt_stop_streaming;
u32 cnt_unprepare_streaming;
#endif
};