Date: Thu, 17 Mar 2016 06:33:14 -0700
From: Tony Lindgren <tony@atomide.com>
To: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Cc: Pali =?utf-8?B?Um9ow6Fy?= <pali.rohar@gmail.com>,
        Sebastian Reichel <sre@kernel.org>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Jarkko Nikula <jarkko.nikula@bitmer.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
Subject: Re: Nokia N900 - audio TPA6130A2 problems
Message-ID: <20160317133313.GL9329@atomide.com>
References: <56E68B71.2030202@ti.com>
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 <56E9A6D9.7000003@ti.com>
 <56E9B910.7000904@gmail.com>
 <20160317004917.GA6750@earth>
 <56EA6326.4000702@gmail.com>
 <20160317130115.GU8413@pali>
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* Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com> [160317 06:11]:
> Hi,
> 
> On 17.03.2016 15:01, Pali Rohár wrote:
> >On Thursday 17 March 2016 09:56:22 Ivaylo Dimitrov wrote:
> >>Hi,
> >>
> >
> >Is camera on same bus as tpa? Maybe this is reason why camera is
> >non-functional too?
> >
> 
> It doesn't matter, all the i2c busses are missing the pullups.
> 
> >>Will fix the board DTS file later on an will report
> >
> >Thanks for investigation! Is that problem in both DTS and also legacy
> >board code?
> >
> 
> I guess legacy board code does not set i2c pull-ups either, as we
> have that problem since the beginning of time. Anyway, let me first
> check if enabling pullups really solves the issue, I hope to test that in a
> couple of hours when I am back home.
> 
> Or you can do it yourself, it is just a matter of replacing PIN_INPUT with
> PIN_INPUT_PULLUP in https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/omap3-n900.dts?id=refs/tags/v4.5#n199
> for all the 3 ic2 busses

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.

Regards,

Tony