Question about snd_soc_card_register()

[Takashi Iwai]

On Thu, 16 Apr 2020 07:52:45 +0200,
Sridharan, Ranjani wrote:
> 
> Hi Takashi,
> 
> While working on implementing the probes features in SOF using a separate card
> for the probe DAI links, I noticed that calling snd_soc_register_card() 
> results in
> incrementing the usage_count for the device that registers the card by 2 and
> it is not decremented until the card is freed.
> 
> Is this the expected behaviour? Typically, we register a separate platform
> device for the Intel machines which in turn register the card and none of them
> ever enable runtime PM. So this has no impact on the parent device's runtime
> PM status. 
> 
> I'd like to avoid creating a separate platform device just to register the
> card if possible while also enabling runtime PM . But when I do this today,
> the device cannot enter runtime suspend at all. Could you please shed some
> light on this?

It's not clear how you see the things.  Which device are you looking
at?  Typically a card object points to two different devices, one is 
the real device that the chip belongs to (card->dev), and another the
own device object for managing the device files (card.card_dev).
And in general, snd_soc_card_register() or snd_card_register() don't
manipulate the runtime PM stuff by itself at all.


thanks,

Takashi