From: Jean Delvare <khali@linux-fr.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>,
Tim Shepard <shep@alum.mit.edu>,
linuxppc-dev@ozlabs.org
Subject: Re: i2c-powermac fails
Date: Thu, 15 Oct 2009 16:05:13 +0200 [thread overview]
Message-ID: <20091015160513.5c356b7e@hyperion.delvare> (raw)
In-Reply-To: <1255605559.2347.102.camel@pasglop>
On Thu, 15 Oct 2009 22:19:19 +1100, Benjamin Herrenschmidt wrote:
> On Thu, 2009-10-15 at 12:49 +0200, Jean Delvare wrote:
> > 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?
>
> No but maybe we are a bit on the "limit" of the device and some
> registers take long to respond than others ?
Unlikely. The ADT7460 can run at I2C clock rates up to 400 kHz while
the Keywest I2C runs at 25, 50 or 100 kHz if I read the code properly.
I don't know what exact speed is used on Tim's system, apparently it is
read from the hardware in the device tree directly?
We could have low_i2c.c log the I2C clock frequency and/or try to force
the lowest speed (25 kHz) and see if it helps, but I very much doubt
it. And I'd rather wait for Tim to report the result with my last patch
first.
--
Jean Delvare
next prev parent reply other threads:[~2009-10-15 14:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-13 9:23 i2c-powermac fails Jean Delvare
2009-10-13 9:32 ` Benjamin Herrenschmidt
2009-10-13 9:49 ` Jean Delvare
2009-10-14 21:02 ` Jean Delvare
2009-10-14 21:26 ` Benjamin Herrenschmidt
2009-10-15 10:49 ` Jean Delvare
2009-10-15 11:19 ` Benjamin Herrenschmidt
2009-10-15 14:05 ` Jean Delvare [this message]
2009-10-16 7:44 ` Jean Delvare
2009-10-16 8:42 ` Benjamin Herrenschmidt
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