Re: [PATCH v9 30/34] ASoC: qcom: qdsp6: Add SND kcontrol for fetching offload status

[Pierre-Louis Bossart]

>>>> Add a kcontrol to the platform sound card to fetch the current offload
>>>> status.  This can allow for userspace to ensure/check which USB SND
>>>> resources are actually busy versus having to attempt opening the USB
>>>> SND
>>>> devices, which will result in an error if offloading is active.
>>>
>>> I think I mentioned this a while back, but why not add the status in the
>>> USB card itself? That's a generic component that all userspace agent
>>> could query. Having a QCOM-specific control doesn't make the life of
>>> userspace easier IMHO.
>>>
>>>
>>
>> Will take a look at this based on the comments you had in the other
>> kcontrol patch.  Seeing if we can move it to a more generic layer.
>>
> 
> I think it would make more sense to see if we can keep all the offload
> kcontrols under the sound card exposed by the platform.  Especially, if
> we are going to modify the components string of the card to signify that
> it supports USB offload.

A two-way relationship would be ideal, i.e.
- the USB card has an indicator that it's currently bound with another
"platform" card that offers optimized offloaded capabilities.
- the platform card has a indicator that it exposes one or more PCM
devices routed to the USB card endpoint.

Android/HAL would typically start with the latter while other more
generic solutions would start from the former.