linux-kernel - Re: [PATCH] ASoC: tlv320aic31xx: Add MICBIAS off setting

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Message-ID: <20180904144159.GC12993@sirena.org.uk>
Date:   Tue, 4 Sep 2018 15:41:59 +0100
From:   Mark Brown <broonie@...nel.org>
To:     "Andrew F. Davis" <afd@...com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: tlv320aic31xx: Add MICBIAS off setting

On Tue, Sep 04, 2018 at 08:55:06AM -0500, Andrew F. Davis wrote:
> On 09/03/2018 06:26 AM, Mark Brown wrote:

> > If we really want to pay attention to something setting this up we'd
> > need to completely remove the widget - what the code is doing at the
> > minute is setting the voltage that the bias will go to when enabled,
> > there's still a widget for turning it on and off.  There's some chance
> > that this will break existing boards.

> Turning on bias is controlled separately, automatically in user-space in
> many cases, not based on the board. The DT needs to have a way to state
> that 0v is the needed bias on this board, without this you can not set
> 0v bias and 2v is chosen by default (which is IMHO should be 0v but that
> would change existing behavior so I won't touch that).

Surely turning on MICBIAS at 0V is equivalent to leaving the bias off?

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