From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Subject: Re: Nokia N900 - audio TPA6130A2 problems
Date: Thu, 17 Mar 2016 09:56:22 +0200
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To: Sebastian Reichel <sre@kernel.org>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>, =?UTF-8?Q?Pali_Roh=c3=a1r?= <pali.rohar@gmail.com>, Peter Ujfalusi <peter.ujfalusi@ti.com>, Jarkko Nikula <jarkko.nikula@bitmer.com>, Tony Lindgren <tony@atomide.com>, Lars-Peter Clausen <lars@metafoo.de>, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Pavel Machek <pavel@ucw.cz>, Aaro Koskinen <aaro.koskinen@iki.fi>, Nishanth Menon <nm@ti.com>, merlijn@wizzup.org
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Hi,

On 17.03.2016 02:49, Sebastian Reichel wrote:
>
> mh both, the power gpio is turned off in tpa6130a2_power(0). I guess
> if you don't see the problem during probe() everything works?
>
> I have another idea though: In opposit to the gpio, the regulator
> may also be referenced by something else/already enabled. I guess
> adding a sleep after the regulator_enable() is worth a try.
>
> Also I wonder if the same happens, if you avoid having the module
> available during boot and instead load it once everything has
> settled. That would rule out any side-effects of other modules
> being probed on the same i2c bus.


Well, I think I've figured it out - input pullups are not enabled
on i2c bus pins, in stock kernel we have:

./devmem2 0x480021BC
Value at address 0x480021BC (0x4001f1bc): 0x1180118

./devmem2 0x480021C0
Value at address 0x480021C0 (0x4001f1c0): 0x1180118

in mainline

./devmem2 0x480021BC
Value at address 0x480021BC (0xb6ff01bc): 0x1000100

./devmem2 0x480021C0
Value at address 0x480021C0 (0xb6f6d1c0): 0x1000100

I wonder how i2c devices work at all :)

Will fix the board DTS file later on an will report

Regards,
Ivo