From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <khali@linux-fr.org>
Received: from poutre.nerim.net (poutre.nerim.net [62.4.16.124])
	by ozlabs.org (Postfix) with ESMTP id BEB20B7B70
	for <linuxppc-dev@ozlabs.org>; Thu, 15 Oct 2009 21:49:27 +1100 (EST)
Date: Thu, 15 Oct 2009 12:49:23 +0200
From: Jean Delvare <khali@linux-fr.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: i2c-powermac fails
Message-ID: <20091015124923.23863a94@hyperion.delvare>
In-Reply-To: <1255555575.2347.56.camel@pasglop>
References: <20091013112304.74083fd1@hyperion.delvare>
	<1255426348.2192.187.camel@pasglop>
	<20091013114948.03608b7f@hyperion.delvare>
	<20091014230252.0d0cba8d@hyperion.delvare>
	<1255555575.2347.56.camel@pasglop>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Cc: Paul Mackerras <paulus@samba.org>, Tim Shepard <shep@alum.mit.edu>,
	linuxppc-dev@ozlabs.org
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
	<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
	<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>

On Thu, 15 Oct 2009 08:26:15 +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2009-10-14 at 23:02 +0200, Jean Delvare wrote:
> > Hi all,
> > 
> > On Tue, 13 Oct 2009 11:49:48 +0200, Jean Delvare wrote:
> > > I2C bus being setup too fast sounds more likely. It might be worth
> > > adding an arbitrary delay after initialization, just to see if it
> > > helps. Not sure where though, as I'm not familiar with the Powermac
> > > initialization steps. Maybe right before i2c_add_adapter() in
> > > i2c_powermac_probe?
> > 
> > Tim, can you please give a try to this patch? Obviously your machine
> > will take 5 additional seconds to boot, and this isn't meant as a real
> > fix, but if it helps, this will be an interesting hint for further
> > debugging attempts.
> 
> Oh, I was actually thinking about the frequency of the I2C clock :-)

Oh. Well, if that was the case, we would see errors all the time, not
just during initialization, right? Or does the I2C clock frequency
change over time somehow?

-- 
Jean Delvare