[pulseaudio-discuss] Configuring alsa mixers in the "off" profile.

[Matti J. Aaltonen]

On 10/06/2011 05:46 PM, ext Mark Brown wrote:
> On Thu, Oct 06, 2011 at 05:11:07PM +0300, Matti J. Aaltonen wrote:
>> On 10/06/2011 04:34 PM, ext Mark Brown wrote:
>>> All the audio power management flows from audio routing - when you
>>> disconnect the audio path that connects the FM radio from an output then
>>> all elements of that path will be powered down (assuming they aren't
>>> also used by other paths).
>> I understand that in the normal digital case. But I'm now kind of
>> fixated to this one example that I've seen.
> The framework makes no distinction between digital and analogue.

OK, I guess that's good.

>
>> In this case we have some alsa devices that behave like you describe
>> above. But then we have an analog amplifier that's connected to
>> to DAC and to the analog radio, the wires are simply soldered to the
>> amplifier inputs.
> They're cross wired?  I guess that could work iff the CODEC and FM radio

Yes they are cross wired... or rather they were cross wired. The analog 
was dropped completely although it would have offered a way to listen to 
the FM radio
with everything else sleeping except for the radio and the headphone amp.


> outputs both behave themselves while disabled.  From a software point of
> view it'll work fine if the radio says when the stream starts and stops.

Fine, now we assume the analog radio is somehow present in the codec. If 
this means that Pulse Audio or any client could the simply open or close 
the corresponding device (which in this case would mean turning the 
radio on or off), and then it would be possible to start listening or 
transmitting by doing a dummy read or write on the device file?

But then I don't get why the radio should be able to say when the 
[analog] "stream" starts and stops (and what do you actually mean by 
that?). Isn't it possible in the above scenario to simply turn on the 
cross wired amp if the analog radio needs it etc. and not the other way 
round?

Are there any good examples that some of "us" should look into?

>
>> What you suggest is that we need "dummy" codec for the analog radio
>> so that we can have it as another audio card in the system...? Now
>> it's starting to sound better.
> No, it should be part of the same sound card.