linux-kernel - Re: [stable] [PATCH] i2c: fix bit algorithm timeout for low values.

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Message-ID: <20090505080543.50b9e569@hyperion.delvare>
Date:	Tue, 5 May 2009 08:05:43 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Greg KH <greg@...ah.com>
Cc:	stable@...nel.org, Dave Airlie <airlied@...hat.com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [stable] [PATCH] i2c: fix bit algorithm timeout for low values.

Hi Greg,

On Mon, 4 May 2009 14:53:25 -0700, Greg KH wrote:
> On Fri, Apr 24, 2009 at 11:42:59AM +0200, Jean Delvare wrote:
> > Hi Dave,
> > 
> > On Fri, 24 Apr 2009 09:09:13 +1000, Dave Airlie wrote:
> > > From: Dave Airlie <airlied@...hat.com>
> > > 
> > > When fetching DDC using i2c algo bit, we were often seeing timeouts
> > > before getting valid EDID on a retry. The VESA spec states 2ms is the
> > > DDC timeout, so when this translates into 1 jiffie and we are close
> > > to the end of the time period, it could return with a timeout less than
> > > 2ms.
> > > 
> > > Change this code to use time_after instead of time_after_eq.
> > > 
> > > Signed-off-by: Dave Airlie <airlied@...hat.com>
> > > ---
> > >  drivers/i2c/algos/i2c-algo-bit.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
> > > index d420cc5..e25e139 100644
> > > --- a/drivers/i2c/algos/i2c-algo-bit.c
> > > +++ b/drivers/i2c/algos/i2c-algo-bit.c
> > > @@ -104,7 +104,7 @@ static int sclhi(struct i2c_algo_bit_data *adap)
> > >  		 * chips may hold it low ("clock stretching") while they
> > >  		 * are processing data internally.
> > >  		 */
> > > -		if (time_after_eq(jiffies, start + adap->timeout))
> > > +		if (time_after(jiffies, start + adap->timeout))
> > >  			return -ETIMEDOUT;
> > >  		cond_resched();
> > >  	}
> > 
> > Applied, thanks. I agree this should go in stable.
> 
> I don't see this in Linus's tree anywhere, am I just missing it?

You're correct, it's not there yet, I'll push it to Linus today. Busy
busy busy.

-- 
Jean Delvare
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