[alsa-devel] [PATCH 7/8] ASoC: codecs: Add AB8500 codec-driver

Ola Lilja ola.o.lilja at stericsson.com
Mon Apr 30 10:50:55 CEST 2012

On 04/27/2012 01:11 PM, Mark Brown wrote:

> On Fri, Apr 27, 2012 at 12:54:59PM +0200, Ola Lilja wrote:
>> On 04/27/2012 11:35 AM, Mark Brown wrote:
>> > What are these regulators?  Are they internal PGA supplies or are they
>> > microphone biases?
>> These are mic-biases.
> OK, then why aren't they hooked up in the board anyway (probably fixed to
> a specific configuration there, though there are some use cases for
> changing)?  This is what other CODEC drivers do with their MICBIASes...

OK, I will have to investigate this possibility then... I'm not certain that we
have this information available from the board in any easy way.

>> > Normally the clocking control is under the control of the machine driver
>> > and if the machine driver wants to offer any options to userspace it'd
>> > provide its own control - usually there's way more stuff going on here
>> > than just selecting a source and much more coordination needed with the
>> > drivers involved.
>> Yes, we are only selecting what clock to request to the clock-driver-code, which
>> then does its magic and taking decisions related to the whole platform.
>> More specifically, in my context (that is audio) we will act upon being in
>> voicecall or not, and in these cases requesting these two different clocks. By
>> design this request comes from audio-code in userspace down to the audio-driver
>> in the kernel. The clock-code will then turn of the clock not needed by us
>> (audio) or any other party.
> So what one would expect there would be that the machine driver would
> figure things out - usually for something like the voice call case the
> machine driver would be doing something like switching to the voice call
> clock when the baseband DAI comes up.

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