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

[Philby John <pjohn-k0rHJ+Hhz/SB+jHODAdFcQ@public.gmane.org>]

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