[alsa-devel] [PATCH 2/2] ASoC: codecs: Add da7218 codec driver

[Opensource [Adam Thomson]]

On November 6, 2015 11:55, Mark Brown wrote:

> > > > I can envisage in a system you may want to choose which capture channels can
> > > > trigger level detection (if any), and this may change depending on the use-case
> > > > at the time, so having it as a control makes sense to me.
> 
> > > What is a "capture channel" here?
> 
> > Input filters 1L/R and 2L/R, which are fed from either Mic1(ADC1) or DMic1L/R
> > and Mic2(ADC2) or DMic2L/R.
> 
> Hang on, is this just recording a DC value with the ADC and then looking
> at that?

The RMS of the Mic signal is taken and compared to the trigger level set. If
it's above that level then an IRQ is raised.