Re: [PATCH/RFC 1/1] recover from davinci i2c time out conditions

From: Craig Matsuura <cmatsuura-/SMLdF/PHsZWk0Htik3J/w@public.gmane.org>
To: davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org
Cc: khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH/RFC 1/1] recover from davinci i2c time out conditions
Date: Fri, 18 Sep 2009 23:12:57 -0600	[thread overview]
Message-ID: <200909182312.58018.cmatsuura@control4.com> (raw)
In-Reply-To: <1248261275.4077.4.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>

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The patch submitted appears specific to the dm355.  The changes are very 
similar to the 2.6.10 kernel from mv.  If the correct gpio's and pinmux are 
disabled/enabled it should work for the dm644x.  

I took the patch from Philby and tried it on our dm6443 platform (on a 2.6.28 
kernel) and it appears to work for the problem we have when the i2c appears to 
lock up.

Craig

On Wednesday 22 July 2009 5:14:35 am Philby John wrote:
> On Wed, 2009-07-22 at 04:03 -0700, Nitin Mahajan wrote:
> > Hello,
> >
> > ----- Original Message ----
> >
> > > From: Philby John <pjohn-k0rHJ+Hhz/SB+jHODAdFcQ@public.gmane.org>
> > > To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > > Cc: khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org; davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org
> > > Sent: Wednesday, July 15, 2009 13:04:27
> > > Subject: [PATCH/RFC 1/1] recover from davinci i2c time out conditions
> > >
> > > >From dbe7e824d576636bb15b82a20fd2557fddc9a8f7 Mon Sep 17 00:00:00 2001
> > >
> > > From: Philby John
> > > Date: Tue, 14 Jul 2009 21:46:47 +0530
> > > Subject: [PATCH] Reset i2c bus to come out of time out conditions
> > >
> > > Get out of i2c time out condition by resetting
> > > the i2c bus. The kernel must be robust enough to
> > > gracefully recover from i2c bus failure without having
> > > to reset the machine. This is done by first NACKing the slave
> > > and then resetting the i2c bus after a certain timeout.
> > >
> > > Signed-off-by: Philby John
> >
> > I tried this on DM6443 based board with 2.6.18 kernel. The result I am
> > posting below. It gives controller time out again and again.
> >
> > dhcppc9 login: i2c_davinci i2c_davinci.1: controller timed out
> > i2c_davinci i2c_davinci.1: initiating i2c bus recovery
> > i2c_davinci i2c_davinci.1: controller timed out
> > i2c_davinci i2c_davinci.1: initiating i2c bus recovery
>
> There is something gravely wrong about this patch and I would submit a
> fix shortly incorporating the review comments. But please be aware that
> I do not guarantee a definitive time line for a fix cause I have much at
> hand at the moment.
>
>
> Regards,
> Philby
>
>
> _______________________________________________
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-- 

Craig Matsuura - Principal Engineer
Control4
11734 South Election Road - Suite 200
Salt Lake City, UT 84020-6432
PH: 801-523-3161
FX: 801-523-3199

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