Subject: Re: Nokia N900 - audio TPA6130A2 problems
To: Tony Lindgren <tony@atomide.com>
References: <20160316144709.GA3389@earth> <56E9A42B.3010209@gmail.com>
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 <20160317133313.GL9329@atomide.com> <56EAB62D.80803@gmail.com>
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Cc: =?UTF-8?Q?Pali_Roh=c3=a1r?= <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
From: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Message-ID: <56EAC62E.7020302@gmail.com>
Date: Thu, 17 Mar 2016 16:58:54 +0200
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Hi,

On 17.03.2016 16:32, Tony Lindgren wrote:
>
> Seems like a bug to me. My bets are on the deferred probe related
> Peter posted.
>

I will test Peter's patch as well, however I really doubt internal 
pull-ups enabled by Nokia to be a bug - keep in mind there are (or at 
least were) enough devices on the field for such a bug to not remain 
unnoticed, esp if it directly affects the signal quality over the i2c bus.

>
> You can calculate the parallel resistor value of the weak internal
> pull with the 1k external pull :)

Sure :)

> If the i2c line pulls are wrong
> the signal quality won't match the spec and you will be getting
> i2c bus errors. If you can read and write to the i2c chip, this
> is not the issue.
>

And it seems stock kernel can read/write without problems with those 
pull-ups enabled.

However, lets continue the discussion after I have tested both the 
Peter's patch and internal pull-ups enabled.

Thanks,
Ivo