Re: pcm512x driver: Mixer control naming issue

[Howard Mitchell <hm@hmbedded.co.uk>]

On 13/03/15 18:27, Mark Brown wrote:
> On Fri, Mar 13, 2015 at 12:41:05PM +0000, Howard Mitchell wrote:
>
>> Boost Volume) provides a boost of +0.8dB. The hardware reset value of both
>> of these gain controls is 0dB, however, in the Raspbian distribution
>> 'Playback Volume' is being defaulted to -6dB.
>>   * Either change the names of these controls to something that's not
>>     affected by the alsa restore mechanism,
> You say "these controls" but it seems like only "Playback Volume" has
> a problem?  My first suggestion would be to define "Analog" or
> "Analogue" as a prefix in ControlNames and then use that, that would
> avoid confusing applications while still fittig in with the naming
> convention.
Yes you are correct that it's only "Playback Volume" that is causing a 
problem. However, I included "Playback Boost Volume" as it also provides 
a selection of analogue gain so I think it should be treated similarly 
for consistency.

Defining a new prefix sounds like a reasonable idea in principle but 
calling it "Analog(ue)" seems like it's saying this is a proper analogue 
volume control whereas these particular controls merely provide very 
limited selections of gain. I could imagine that at some point in the 
future a default for "Analogue Playback Volume" may well be added to 
"alsactl restore" and then we end up back in the same situation. How 
about defining a prefix that is documented as saying that a default 
should not be used if there's nothing in asound.state for that control?

>>   * or remove them as mixer controls, but make them accessible some
>>     other way - e.g. device tree.
> It may not be policy that someone wants to tweak at runtime on your
> board but it almost certainly will be on someone's board.
>
Fair enough, if that's the general alsa ethos I'm happy to go along with it.