[alsa-devel] ASoC: Machine Driver Interaction with Codec Drivers

[Lars-Peter Clausen]

On 06/13/2016 11:37 PM, Jeremy McDermond wrote:
> Thanks to everyone for their responses on this.  I’m glad I wasn’t missing
> anything stupid.
> 
> Lars-Peter Clausen <lars at metafoo.de> wrote:
> 
>> And today basically
>> everybody takes care of hiding the controls from userspace.
> 
> What are people’s strategies for doing this from userspace?  I’ve ingested
> all the docs I could about .asoundrc but wasn’t seeing anything obvious
> where I could hard wire controls.  I could populate alsa.state, but that’s a
> really ugly solution.

There are different solutions used by different projects.

Some just hardcode the list of exposed controls in their sound daemon
(although that's not something I'd recommend).

There is ALSA UCM
(http://www.alsa-project.org/main/index.php/Use_Case_Manager
http://www.slimlogic.co.uk/2009/02/alsa-use-case-manager/) which allows you
to define groups of control settings as profiles and also define which
individual controls to expose.

And Android has something similar to UCM, but I can't remember the name
right now.

- Lars