From mboxrd@z Thu Jan  1 00:00:00 1970
From: alexandre.belloni@free-electrons.com (Alexandre Belloni)
Date: Mon, 9 Mar 2015 08:55:46 +0100
Subject: [PATCH v2 5/6] watchdog: at91sam9: request the irq with
 IRQF_NO_SUSPEND
In-Reply-To: <1615214.0rkGfM1gZL@vostro.rjw.lan>
References: <1425287898-15093-6-git-send-email-boris.brezillon@free-electrons.com>
 <20150307110645.GW3989@piout.net> <20150307112932.GA1372@amd>
 <1615214.0rkGfM1gZL@vostro.rjw.lan>
Message-ID: <20150309075546.GY3989@piout.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

On 08/03/2015 at 02:12:53 +0100, Rafael J. Wysocki wrote :
> > > I think you misunderstood, that is exactly the expected behaviour. This
> > > is hardware defined. Once the watchdog is started, nobody can stop it.
> > > Trying to change the mode register will result in a reset of the
> > > SoC.
> > 
> > Well, it boils down to "what is stronger". Desire to suspend the
> > system, or desire to reboot the system.
> > 
> > It is "echo mem > state", not "echo reboot > state".
> > 
> > > It is documented in the datasheet and any user wanting another behaviour
> > > is out of luck.
> > 
> > Actaully, your platform should just refuse to enter suspend-to-RAM
> > when hw watchdog is enabled.
> 
> Quite likely, depending on how exactly the suspend is implemented.
>

We've had absolutely zero complain on that. It is quite clear in the
datasheet that failing to refresh the watchdog once started will lead to
a reset and that it is impossible to stop.
It is actually quite convenient to also ensure that you can actually
wake up from suspend because that can obviously go wrong.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com