linux-kernel - RE: [PATCH AUTOSEL for 4.9 31/56] ASoC: da7218: Set DAI output pin high impedance when not in use

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Message-ID: <2E89032DDAA8B9408CB92943514A0337014C1AEF3B@SW-EX-MBX01.diasemi.com>
Date:   Wed, 15 Nov 2017 16:55:03 +0000
From:   Adam Thomson <Adam.Thomson.Opensource@...semi.com>
To:     "alexander.levin@...izon.com" <alexander.levin@...izon.com>,
        Mark Brown <broonie@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Subject: RE: [PATCH AUTOSEL for 4.9 31/56] ASoC: da7218: Set DAI output pin
 high impedance when not in use

On 15 November 2017 16:43, alexander.levin@...izon.com wrote:

> On Wed, Nov 15, 2017 at 12:19:18PM +0000, Mark Brown wrote:
> >On Wed, Nov 15, 2017 at 02:45:42AM +0000, alexander.levin@...izon.com wrote:
> >
> >> This patch updates the AIF_OUT widget to set the DAI output pin of
> >> the device as high impedance when not in use.
> >
> >This will leave the line floating which EEs don't always like.  It's
> >probably OK and hasn't lead to any reports in mainline yet but still...
> 
> The idea I got from the patch is that output will not be working if
> there are multiple codecs?

Yes, if there are multiple codecs sharing the same DAI line for capture as
DA7217/8, and we don't set this to high impedance, then it will interfere with
the other codecs' capture data.