linux-kernel - Re: [PATCH 5/5] i2c: octeon,thunderx: Limit register access retries

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Date:   Thu, 22 Sep 2016 18:40:18 +0200
From:   Jan Glauber <jan.glauber@...iumnetworks.com>
To:     Wolfram Sang <wsa@...-dreams.de>
CC:     <linux-kernel@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
        "Bazhenov, Dmitry" <dmitry.bazhenov@...iga.com>
Subject: Re: [PATCH 5/5] i2c: octeon,thunderx: Limit register access retries

On Wed, Sep 21, 2016 at 11:03:35PM +0200, Wolfram Sang wrote:
> On Wed, Sep 21, 2016 at 08:51:06AM +0200, Jan Glauber wrote:
> > Do not infinitely retry register readq and writeq operations
> > in order to not lock up the CPU in case the TWSI gets stuck.
> > 
> > Return -EIO in case of a failed data read. For all other
> > cases just return so subsequent operations will fail
> > and trigger the recovery.
> > 
> > Signed-off-by: Jan Glauber <jglauber@...ium.com>
> 
> I didn't really check, but have you considered using
> readq_poll_timeout() from iopoll.h?
> 

Indeed, readq_poll_timeout() fits quite well here. It will lose some cycles
on mips but I'm not convinced that matters with i2c.

That would be the first user of readq_poll_timeout() in the kernel :)

--Jan