linux-kernel - Re: [PATCH v4 1/2] watchdog: New watchdog driver for MEN A21 watchdogs

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Date:	Thu, 30 May 2013 23:52:03 +0200
From:	Wim Van Sebroeck <wim@...ana.be>
To:	Johannes Thumshirn <johannes.thumshirn@....de>
Cc:	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] watchdog: New watchdog driver for MEN A21 watchdogs

Hi Johannes,

> On Mon, May 27, 2013 at 08:25:54PM +0200, Wim Van Sebroeck wrote:
> [...]
> > > +	watchdog_set_drvdata(&a21_wdt, drv);
> >
> > I am missing the initialisation of the watchdog's timeout value here...
> 
> This watchdog only knows two timeout values, 1s and 30s with the constraint
> that you can't go back to 30s once your in a 1s timeout without a reset of the
> CPLD. I could initially set it to 30s but that would be redundant.

Yes, but if I use a WDIOC_GETTIMEOUT ioctl call then I will get 0 because
you didn't initialize a21_wdt.timeout so you don't know wether or not
it's 30 or 1.

You can also set it default to 1 and use a timer to do the bridge between userspace
and an in kernel timer of 0.5msec. (see git/linux-watchdog/drivers/watchdog/pika_wdt.c
as an example).

Kind regards,
Wim.

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