From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivaylo Dimitrov Subject: Re: Nokia N900 - audio TPA6130A2 problems Date: Thu, 17 Mar 2016 16:58:54 +0200 Message-ID: <56EAC62E.7020302@gmail.com> References: <20160316144709.GA3389@earth> <56E9A42B.3010209@gmail.com> <56E9A6D9.7000003@ti.com> <56E9B910.7000904@gmail.com> <20160317004917.GA6750@earth> <56EA6326.4000702@gmail.com> <20160317130115.GU8413@pali> <56EAACF4.2040005@gmail.com> <20160317133313.GL9329@atomide.com> <56EAB62D.80803@gmail.com> <20160317143204.GM9329@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160317143204.GM9329@atomide.com> Sender: linux-kernel-owner@vger.kernel.org To: Tony Lindgren Cc: =?UTF-8?Q?Pali_Roh=c3=a1r?= , Sebastian Reichel , Grygorii Strashko , Peter Ujfalusi , Jarkko Nikula , Lars-Peter Clausen , linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Pavel Machek , Aaro Koskinen , Nishanth Menon , merlijn@wizzup.org List-Id: linux-omap@vger.kernel.org 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