Date:	Thu, 4 Feb 2016 08:26:49 -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 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).

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.

> +
> +	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?

> +
> +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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