linux-kernel - Re: [PATCH v1 1/4] ASoC: codecs: tfa989x: Add switch to allow disabling amplifier

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Date:   Thu, 28 Oct 2021 09:22:05 +0200
From:   Stephan Gerhold <stephan@...hold.net>
To:     Mark Brown <broonie@...nel.org>
Cc:     Vincent Knecht <vincent.knecht@...loo.org>, lgirdwood@...il.com,
        robh+dt@...nel.org, perex@...ex.cz, tiwai@...e.com,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v1 1/4] ASoC: codecs: tfa989x: Add switch to allow
 disabling amplifier

On Mon, Oct 25, 2021 at 11:52:04AM +0100, Mark Brown wrote:
> On Sun, Oct 24, 2021 at 10:58:37AM +0200, Vincent Knecht wrote:
> > From: Stephan Gerhold <stephan@...hold.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?

Thanks for the suggestion! For some reason I was not aware of the pin
switch mechanism... :) We have tried this and it seems to work fine.
I will submit a separate series to allow setting up the pin switches
for the qcom sound cards instead.

The other patches in this series are independent of this one and still
apply cleanly for me. Can you just ignore PATCH 1/4 or would you prefer
a resend without this patch?

Thanks,
Stephan