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

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Date:   Mon, 9 Jan 2017 14:13:17 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Mark Brown <broonie@...nel.org>
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 Monday 09 January 2017 11:27:49 Mark Brown wrote:
> 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.

So... can I call snd_soc_dapm_mutex_lock(dapm) at function startup,
start doing cable detection and when needed call this?

snd_soc_dapm_enable_pin_unlocked(dapm, "HS Mic");
snd_soc_dapm_sync_unlocked(dapm);

And at the end of function revert back "HS Mic" pin status and call
snd_soc_dapm_mutex_unlock(dapm)?

-- 
Pali Rohár
pali.rohar@...il.com