Message-ID: <56B91E0A.90705@osg.samsung.com>
Date:	Mon, 8 Feb 2016 16:00:26 -0700
From:	Shuah Khan <shuahkh@....samsung.com>
To:	Mauro Carvalho Chehab <mchehab@....samsung.com>
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	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	alsa-devel@...a-project.org, Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH v2 20/22] media: au0828 add enable, disable source
 handlers

On 02/08/2016 03:42 PM, Shuah Khan wrote:
> 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()?
> 
> 
>        /* 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?

On analog side, there are a few ioctls that
change the configuration on the tuner way
before stream on step. Is there a reason to
separate the setup_link() and pipeline_start()
steps? I can separate these two steps, but I
am not really seeing the reason for that.

>>
>>> +	/*
>>> +	 * 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
>>>  };
>>>  
> 
> 


-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@....samsung.com | (970) 217-8978

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