linux-kernel - Re: Nokia N900 - audio TPA6130A2 problems

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Message-ID: <56EAB62D.80803@gmail.com>
Date:	Thu, 17 Mar 2016 15:50:37 +0200
From:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Pali Rohár <pali.rohar@...il.com>,
	Sebastian Reichel <sre@...nel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Jarkko Nikula <jarkko.nikula@...mer.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	Pavel Machek <pavel@....cz>,
	Aaro Koskinen <aaro.koskinen@....fi>,
	Nishanth Menon <nm@...com>, merlijn@...zup.org
Subject: Re: Nokia N900 - audio TPA6130A2 problems

Hi,

On 17.03.2016 15:33, Tony Lindgren wrote:
>
> Check the schematics. If the hardware has external pull-ups on a
> line then don't enable the internal pull-ups. Otherwise both the
> external and intenal pulls are parallel the pull value will be
> wrong. My guess is that on n900 all the i2c lines have external
> pulls.

There are, 1k connected to VIO_18, but still, stock Nokia kernel enables 
the internal pull-ups as well. I doubt Nokia devs did that by mistake. 
Could it be that VIO_18 is disabled by the time  TPA6130A2 is probed?

Also, what is the problem to have both internal and external pull-ups in 
parallel?

Regards,
Ivo