Re: [PATCH 3/3] vimc: Join pipeline if one already exists

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

Hi Helen,

Thanks for your feedback.

On 2019-07-09 15:24:10 -0300, Helen Koike wrote:
> Hi Niklas,
> 
> Thanks for the patch (and sorry for my late reply).
> 
> On 5/17/19 10:07 PM, Niklas Söderlund wrote:
> > A sensor which is running is already part of a pipeline and trying to
> > start a new pipeline is not possible. This prevents two capture devices
> > connected to the same sensor from running at the same time.
> > 
> > Instead of failing to start the second capture device allow it to join
> > the already running pipeline by looking it up at the sensor. This allows
> > two (or more) capture devices to independently be started and stopped
> > while still being connected to the same sensor.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> > ---
> >  drivers/media/platform/vimc/vimc-capture.c | 35 +++++++++++++++++++++-
> >  1 file changed, 34 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/vimc/vimc-capture.c b/drivers/media/platform/vimc/vimc-capture.c
> > index e7d0fc2228a6f0c1..f9eb1e327e311b4a 100644
> > --- a/drivers/media/platform/vimc/vimc-capture.c
> > +++ b/drivers/media/platform/vimc/vimc-capture.c
> > @@ -264,16 +264,49 @@ static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
> >  	spin_unlock(&vcap->qlock);
> >  }
> >  
> > +static struct media_entity *vimc_cap_get_sensor(struct vimc_cap_device *vcap)
> > +{
> > +	struct media_entity *entity = &vcap->vdev.entity;
> > +	struct media_device *mdev = entity->graph_obj.mdev;
> > +	struct media_graph graph;
> > +
> > +	mutex_lock(&mdev->graph_mutex);
> > +	if (media_graph_walk_init(&graph, mdev)) {
> > +		mutex_unlock(&mdev->graph_mutex);
> > +		return NULL;
> > +	}
> > +
> > +	media_graph_walk_start(&graph, entity);
> > +
> > +	while ((entity = media_graph_walk_next(&graph)))
> > +		if (entity->function == MEDIA_ENT_F_CAM_SENSOR)
> > +			break;
> 
> I was wondering if it should search up to the sensor, or if it could just search the first entity with a pipe object, what do you think?
> Like this it should work with an output device instead of a sensor.

I think that might be a good idea, I will see what I can do for v2.

> 
> Regards,
> Helen
> 
> > +
> > +	mutex_unlock(&mdev->graph_mutex);
> > +
> > +	media_graph_walk_cleanup(&graph);
> > +
> > +	return entity;
> > +}
> > +
> >  static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
> >  {
> >  	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> >  	struct media_entity *entity = &vcap->vdev.entity;
> > +	struct media_pipeline *pipe = NULL;
> > +	struct media_entity *sensorent;
> >  	int ret;
> >  
> >  	vcap->sequence = 0;
> >  
> >  	/* Start the media pipeline */
> > -	ret = media_pipeline_start(entity, &vcap->stream.pipe);
> > +	sensorent = vimc_cap_get_sensor(vcap);
> > +	if (sensorent && sensorent->pipe)
> > +		pipe = sensorent->pipe;
> > +	else
> > +		pipe = &vcap->stream.pipe;
> > +
> > +	ret = media_pipeline_start(entity, pipe);
> >  	if (ret) {
> >  		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> >  		return ret;
> > 

-- 
Regards,
Niklas Söderlund