[alsa-devel] [RFC don't apply] ASoC: Add support for optional auxiliary dailess codecs

Peter Ujfalusi peter.ujfalusi at nokia.com
Fri Nov 26 13:19:42 CET 2010


On Friday 26 November 2010 09:25:24 ext Jarkko Nikula wrote:
> And codecs can be used as an amplifer only by not connecting the DAI.
> Like if codec chip is cheaper or better available than amplifier or if
> multicodec package saves board space compared to separate codec and
> amplifier chips.

We could as well see these things as components on the audio path.
A standard CODEC would have DAI + DAPM (analog/digital routings, amps) + gain 
In case of an external amplifier we only have the DAPM part + gain control.

If a component has DAI, than the normal PCM operations would apply to them, if 
the component does not have DAI, than those are not applicable.
I'm not sure, but I think we do have some level of separation of DAPM and PCM 
operations, right? So why not to utilize, and extend that route?
All component drivers would use the same registration, core would knows which 
component has DAI, and which does not. Machine driver could specify a list of 
components, provides the DAPM connection between the components.

If DAPM core knows which widget belongs to which component, than I see no real 
problem with this method. The DAPM would work just fine. The PCM operatins would 
only apply to component with DAI.

> If I counted correctly we have currently only three amplifier drivers:
> tpa6130a2.c, wm2000.c and wm9090.c so separation doesn't sound worth of
> trouble at this point as the core serves well those cases also.

One more: max9877, if I recall correctly that was the first amp driver?


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