linux-kernel - Re: [PATCH v3 2/2] watchdog: fix w83627hf

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Message-ID: <20130403155026.GA4549@roeck-us.net>
Date:	Wed, 3 Apr 2013 08:50:26 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Tony Chung <tonychung00@...il.com>
Cc:	Wim Van Sebroeck <wim@...ana.be>, linux-watchdog@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] watchdog: fix w83627hf_wdt clear timeout expired

On Wed, Apr 03, 2013 at 08:06:59AM -0700, Tony Chung wrote:
> On Tue, Apr 2, 2013 at 9:21 PM, Guenter Roeck <linux@...ck-us.net> wrote:
> 
> >
> >
> > What is the exact chip type in your system ? I want to have a look into the
> > datasheet; maybe I can find out how it can trigger without causing a reset.
> 
> Winbond 83627HF chip
> 
> I believe BIOS has watchdog disabled otherwise it would have reboot the box.
> However, the timer just start counting.
> 
> Comparing to ipmi_watchdog, you can do this:
> modprobe ipmi_watchdog ... start_now=0 ...action=<>  nowayout=1
> 
> So it is possible to load the driver without start counting.
> 
That is a different driver, though. you don't have the start_now option here.

> Notice it is an else, so t is actually 0 already (i.e. expired or
> never start running):

Still no idea why that would cause the system to reboot when you reset
the trigger without setting t to 0 again (or why the system doesn't reset
in the first place if the watchdog already triggered).

I am not really sure what the best approach is here, so let's leave it
up to the maintainer to decide which way to go.

Thanks,
Guenter
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