[alsa-devel] UCM: Possible snd_use_case_get enhancements

[Liam Girdwood]

On 03/06/11 22:11, Stephen Warren wrote:
> Liam,
> 
> The recent patches I posted allow querying a modifier/device's supported/
> conflicting device list from a modifier/device either within the
> currently active verb (if any) or an explicitly defined verb.
> 
> I figured a similar enhancement to snd_use_case_get might be useful; i.e.
> to allow querying within a specific verb, and also to indicate that one
> shouldn't fall back to a verb, or overall values. I'd propose something
> like this:
> 
> NAME[[=]/<modifier>|<device>[/[=]<verb>]]
> 
> The "=" would prevent fallback to a "higher" object if present. So for
> example:
> 
> Current verb, not from device or modifier, with fallback to verb and
> ValueDefaults:
> 
> PlaybackVolume
> 
> Current verb, from device/modifier with fallback to verb and
> ValueDefaults:
> 
> PlaybackVolume/Play Music
> 
> Current verb, from dev/mod without fallback to verb or ValueDefaults:
> 
> PlaybackVolume/=Play Music
> 
> Specify a verb and dev/mod, but allow fallback to verb or ValueDefaults:
> 
> PlaybackVolume/Play Music/HiFi
> 
> Specify a verb and dev/mod, but no fallback to verb or ValueDefaults:
> 
> PlaybackVolume/=Play Music/=HiFi
> 
> One can also query from just a verb, with/without fallback:
> 
> PlaybackVolume//HiFi
> PlaybackVolume//=HiFi
> 
> Or current verb with no fallback:
> 
> PlaybackVolume//=
> 
> Does this seem useful, and a sane query string syntax?
> 

Sounds fine to me.

> An alternative would be to drop the added "=" stuff, and never auto-
> fallback. However, that'd be a regression relative to current
> functionality, force clients to implement fallback themselves, and make
> querying ValueDefaults hard.
> 

Thanks

Liam