On Sun, Oct 24, 2021 at 10:58:37AM +0200, Vincent Knecht wrote:

From: Stephan Gerhold <stephan@gerhold.net>

In some configurations it may be necessary to explicitly disable
the amplifier with an ALSA mixer. An example for this is a stereo
setup with two TFA989X. If only one of them should be used (e.g.
to use it as an earpiece) the other one must be explicitly disabled.

Add a virtual "Amp Switch" to implement that. There is no register
for this (SND_SOC_NOPM) so it only prevents DAPM from activating
the amplifier. Also it is inverted (= enabled by default) for
compatibility with devices that do not need this functionality.

Why can you not use a standard pin switch on the speaker output for
this?