Re: [media-workshop] [PATCH v8.4 81/83] [media] media-entity: init pads on entity init if was registered before

[Javier Martinez Canillas <javier@osg.samsung.com>]

Hello Laurent,

On 11/23/2015 01:20 PM, Laurent Pinchart wrote:
> Hi Javier,
> 
> (Replying to linux-media instead of media-workshop, I can't find this patch in 
> my linux-media folder)
>
> Thank you for the patch.
>

Thanks for your feedback.
 
> On Monday 12 October 2015 13:44:10 Mauro Carvalho Chehab wrote:
>> From: Javier Martinez Canillas <javier@osg.samsung.com>
>>
>> If an entity is registered with a media device before is initialized
>> with media_device_register_entity(), the number of pads won't be set
>> so media_device_register_entity() won't create pad objects and add
>> it to the media device pads list.
>>
>> Do this at entity initialization time if the entity was registered
>> before so the graph is complete and correct regardless of the order
>> in which the entities are initialized and registered.
> 
> We now have two places where the pads graph objects are initialized and that 
> looks like a bug to me as media_gobj_init() allocates IDs and, even worse, 
> adds the entity to the media device entities list.
>

Yes but the idea of this patch was in fact to make it less error prone and
more robust since entities could either be initialized and later registered
or first be registered and then later initialized.
 
> We need to standardize on where graph objects are initialized across the 
> different kind of objects and document this clearly otherwise drivers will get 
> it wrong.
>

I'm OK with having more strict rules of the order in which objects should
be initialized and registered and force all drivers to follow these docs.

>> Suggested-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

This patch was suggested by Mauro so I'll also let him to comment what he
prefers or if he has another opinion on this.

>> Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
>> ---
>>  drivers/media/media-entity.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
>> index f28265864b76..2c984fb7d497 100644
>> --- a/drivers/media/media-entity.c
>> +++ b/drivers/media/media-entity.c
>> @@ -238,6 +238,7 @@ int
>>  media_entity_init(struct media_entity *entity, u16 num_pads,
>>  		  struct media_pad *pads)
>>  {
>> +	struct media_device *mdev = entity->graph_obj.mdev;
>>  	unsigned int i;
>>
>>  	entity->group_id = 0;
>> @@ -246,11 +247,20 @@ media_entity_init(struct media_entity *entity, u16
>> num_pads, entity->num_pads = num_pads;
>>  	entity->pads = pads;
>>
>> +	if (mdev)
>> +		spin_lock(&mdev->lock);
>> +
>>  	for (i = 0; i < num_pads; i++) {
>>  		pads[i].entity = entity;
>>  		pads[i].index = i;
>> +		if (mdev)
>> +			media_gobj_init(mdev, MEDIA_GRAPH_PAD,
>> +					&entity->pads[i].graph_obj);
>>  	}
>>
>> +	if (mdev)
>> +		spin_unlock(&mdev->lock);
>> +
>>  	return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(media_entity_init);
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America