Date:	Tue, 9 Feb 2016 08:51:57 -0200
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Shuah Khan <shuahkh@....samsung.com>
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Subject: Re: [PATCH v2 20/22] media: au0828 add enable, disable source
 handlers

Em Mon, 08 Feb 2016 15:42:15 -0700
Shuah Khan <shuahkh@....samsung.com> escreveu:

> On 02/04/2016 03:26 AM, Mauro Carvalho Chehab wrote:
> > Em Wed, 03 Feb 2016 21:03:52 -0700
> > Shuah Khan <shuahkh@....samsung.com> escreveu:
> >   
> >> Add enable_source and disable_source handlers.
> >> The enable source handler is called from
> >> v4l2-core, dvb-core, and ALSA drivers to check
> >> if the shared media source is free. The disable
> >> source handler is called to release the shared
> >> media source.
> >>
> >> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> >> ---
> >>  drivers/media/usb/au0828/au0828-core.c | 149 +++++++++++++++++++++++++++++++++
> >>  drivers/media/usb/au0828/au0828.h      |   3 +
> >>  2 files changed, 152 insertions(+)
> >>
> >> diff --git a/drivers/media/usb/au0828/au0828-core.c b/drivers/media/usb/au0828/au0828-core.c
> >> index 4c90f28..fd2265c 100644
> >> --- a/drivers/media/usb/au0828/au0828-core.c
> >> +++ b/drivers/media/usb/au0828/au0828-core.c
> >> @@ -282,6 +282,7 @@ static int au0828_create_media_graph(struct au0828_dev *dev)
> >>  		return -EINVAL;
> >>  
> >>  	if (tuner) {
> >> +		dev->tuner = tuner;
> >>  		/* create tuner to decoder link in deactivated state */
> >>  		ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
> >>  					    decoder, 0, 0);
> >> @@ -373,6 +374,150 @@ void au0828_media_graph_notify(struct media_entity *new, void *notify_data)
> >>  #endif
> >>  }
> >>  
> >> +static int au0828_enable_source(struct media_entity *entity,
> >> +				struct media_pipeline *pipe)
> >> +{
> >> +#ifdef CONFIG_MEDIA_CONTROLLER
> >> +	struct media_entity  *source;
> >> +	struct media_entity *sink;
> >> +	struct media_link *link, *found_link = NULL;
> >> +	int ret = 0;
> >> +	struct media_device *mdev = entity->graph_obj.mdev;
> >> +	struct au0828_dev *dev;
> >> +
> >> +	if (!mdev)
> >> +		return -ENODEV;
> >> +
> >> +	/* for Audio and Video entities, source is the decoder */
> >> +	mutex_lock(&mdev->graph_mutex);
> >> +
> >> +	dev = mdev->source_priv;
> >> +	if (!dev->tuner || !dev->decoder) {
> >> +		ret = -ENODEV;
> >> +		goto end;
> >> +	}  
> > 
> > This is wrong. There are devices without tuner (capture devices) and
> > without analog decoder (pure DVB devices).  
> 
> Removed linux-api from the list.
> 
> Yes this logic is making an assumption that both
> decoder and tuner are present. Based on your comment
> here, is the following check for decoder in 
> au0828_create_media_graph() incorrect? When decoder
> is null, au0828_usb_probe() bails out. Please see
> au0828_create_media_graph() return handling in
> au0828_usb_probe()?

It seems so. at its current state, au0828 always register a V4L2
node, except if !CONFIG_VIDEO_AU0828_V4L2. So, it is missing a

#ifdef CONFIG_VIDEO_AU0828_V4L2

inside it. I'll write such fixup.


> 
> 
>        /* Something bad happened! */
>         if (!decoder)
>                 return -EINVAL;
> 
> > 
> > In the case of pure DVB devices (e. g. no dev->decoder), it should
> > just enable the DVB path.
> > 
> > In the case of devices without tuner, it should use the same logic
> > needed to handle the S-Video/Composite connector inputs.
> > 
> > Btw, I'm not seeing how this logic would do the right thing if the user
> > selects either S-Video or Composite connectors.
> >   
> >> +
> >> +	/*
> >> +	 * For Audio and V4L2 entity, find the link to which decoder
> >> +	 * is the sink. Look for an active link between decoder and
> >> +	 * tuner, if one exists, nothing to do. If not, look for any
> >> +	 * active links between tuner and any other entity. If one
> >> +	 * exists, tuner is busy. If tuner is free, setup link and
> >> +	 * start pipeline from source (tuner).
> >> +	 * For DVB FE entity, the source for the link is the tuner.
> >> +	 * Check if tuner is available and setup link and start
> >> +	 * pipeline.
> >> +	*/
> >> +	if (entity->function != MEDIA_ENT_F_DTV_DEMOD)
> >> +		sink = dev->decoder;
> >> +	else
> >> +		sink = entity;
> >> +
> >> +	/* Is an active link between sink and tuner */
> >> +	if (dev->active_link) {
> >> +		if (dev->active_link->sink->entity == sink &&
> >> +		    dev->active_link->source->entity == dev->tuner) {
> >> +			ret = 0;
> >> +			goto end;
> >> +		} else {
> >> +			ret = -EBUSY;
> >> +			goto end;
> >> +		}
> >> +	}
> >> +
> >> +	list_for_each_entry(link, &sink->links, list) {
> >> +		/* Check sink, and source */
> >> +		if (link->sink->entity == sink &&
> >> +		    link->source->entity == dev->tuner) {
> >> +			found_link = link;
> >> +			break;
> >> +		}
> >> +	}
> >> +
> >> +	if (!found_link) {
> >> +		ret = -ENODEV;
> >> +		goto end;
> >> +	}
> >> +
> >> +	/* activate link between source and sink and start pipeline */
> >> +	source = found_link->source->entity;
> >> +	ret = __media_entity_setup_link(found_link, MEDIA_LNK_FL_ENABLED);
> >> +	if (ret) {
> >> +		pr_err(
> >> +			"Activate tuner link %s->%s. Error %d\n",
> >> +			source->name, sink->name, ret);
> >> +		goto end;
> >> +	}
> >> +
> >> +	ret = __media_entity_pipeline_start(entity, pipe);
> >> +	if (ret) {
> >> +		pr_err("Start Pipeline: %s->%s Error %d\n",
> >> +			source->name, entity->name, ret);
> >> +		ret = __media_entity_setup_link(found_link, 0);
> >> +		pr_err("Deactive link Error %d\n", ret);
> >> +		goto end;
> >> +	}  
> > 
> > Hmm... isn't it to early to activate the pipeline here? My original
> > guess is that, on the analog side, this should happen only at the stream
> > on code. Wouldn't this break apps like mythTV?
> >   
> >> +	/*
> >> +	 * save active link and active link owner to avoid audio
> >> +	 * deactivating video owned link from disable_source and
> >> +	 * vice versa
> >> +	*/
> >> +	dev->active_link = found_link;
> >> +	dev->active_link_owner = entity;
> >> +end:
> >> +	mutex_unlock(&mdev->graph_mutex);
> >> +	pr_debug("au0828_enable_source() end %s %d %d\n",
> >> +		entity->name, entity->function, ret);
> >> +	return ret;
> >> +#endif
> >> +	return 0;
> >> +}
> >> +
> >> +static void au0828_disable_source(struct media_entity *entity)
> >> +{
> >> +#ifdef CONFIG_MEDIA_CONTROLLER
> >> +	struct media_entity *sink;
> >> +	int ret = 0;
> >> +	struct media_device *mdev = entity->graph_obj.mdev;
> >> +	struct au0828_dev *dev;
> >> +
> >> +	if (!mdev)
> >> +		return;
> >> +
> >> +	mutex_lock(&mdev->graph_mutex);
> >> +	dev = mdev->source_priv;
> >> +	if (!dev->tuner || !dev->decoder || !dev->active_link) {
> >> +		ret = -ENODEV;
> >> +		goto end;
> >> +	}  
> > 
> > Same note as before.  
> 
> Same comment as before here about au0828_create_media_graph()
> and au0828_usb_probe() handling.
> 
> >   
> >> +
> >> +	if (entity->function != MEDIA_ENT_F_DTV_DEMOD)
> >> +		sink = dev->decoder;
> >> +	else
> >> +		sink = entity;
> >> +
> >> +	/* link is active - stop pipeline from source (tuner) */
> >> +	if (dev->active_link && dev->active_link->sink->entity == sink &&
> >> +	    dev->active_link->source->entity == dev->tuner) {
> >> +		/*
> >> +		 * prevent video from deactivating link when audio
> >> +		 * has active pipeline
> >> +		*/
> >> +		if (dev->active_link_owner != entity)
> >> +			goto end;
> >> +		__media_entity_pipeline_stop(entity);
> >> +		ret = __media_entity_setup_link(dev->active_link, 0);
> >> +		if (ret)
> >> +			pr_err("Deactive link Error %d\n", ret);
> >> +		dev->active_link = NULL;
> >> +		dev->active_link_owner = NULL;
> >> +	}  
> > 
> > Most code here looks like the one at au0828_enable_source(). Wouldn't
> > be simpler to merge those code and add a "bool enable" to the function
> > parameters?  
> 
> I would rather keep these separate. A very short
> section is common really.
> 
> thanks,
> -- Shuah
> 
> >   
> >> +
> >> +end:
> >> +	mutex_unlock(&mdev->graph_mutex);
> >> +#endif
> >> +}
> >> +
> >>  static int au0828_media_device_register(struct au0828_dev *dev,
> >>  					struct usb_device *udev)
> >>  {
> >> @@ -403,6 +548,10 @@ static int au0828_media_device_register(struct au0828_dev *dev,
> >>  			ret);
> >>  		return ret;
> >>  	}
> >> +	/* set enable_source */
> >> +	dev->media_dev->source_priv = (void *) dev;
> >> +	dev->media_dev->enable_source = au0828_enable_source;
> >> +	dev->media_dev->disable_source = au0828_disable_source;
> >>  #endif
> >>  	return 0;
> >>  }
> >> diff --git a/drivers/media/usb/au0828/au0828.h b/drivers/media/usb/au0828/au0828.h
> >> index 54379ec..a7c88a1 100644
> >> --- a/drivers/media/usb/au0828/au0828.h
> >> +++ b/drivers/media/usb/au0828/au0828.h
> >> @@ -284,6 +284,9 @@ struct au0828_dev {
> >>  	struct media_entity input_ent[AU0828_MAX_INPUT];
> >>  	struct media_pad input_pad[AU0828_MAX_INPUT];
> >>  	struct media_entity_notify entity_notify;
> >> +	struct media_entity *tuner;
> >> +	struct media_link *active_link;
> >> +	struct media_entity *active_link_owner;
> >>  #endif
> >>  };
> >>    
> 
> 

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