linux-kernel - Re: Nokia N900 headset detection & MIC Bias + TVOUT

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Date:   Mon, 9 Jan 2017 11:27:49 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Jarkko Nikula <jarkko.nikula@...mer.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Nishanth Menon <nm@...com>, Sebastian Reichel <sre@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        joerg Reisenweber <joerg@...nmoko.org>,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Nokia N900 headset detection & MIC Bias + TVOUT

On Sat, Jan 07, 2017 at 12:07:49AM +0100, Pali Rohár wrote:

> All that is needed in N900 sound driver, file sound/soc/omap/rx51.c. Can 
> you help me which functions should I call to enable/disable it 
> correctly? In headset detection code I need to be sure that nobody 
> (other kernel drivers or userspace via alsamixer) except current 
> function could change Bias settings.

> MIC Bias is controlled by MICBIAS_CTRL in aic34 'B' part codec, file 
> tlv320aic3x.c.

Microphone biases are normally controlled by supply widgets and managed
via DAPM.  You can see quite a few examples of this in existing drivers.

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