[PATCH v2 5/6] watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND

Alexandre Belloni alexandre.belloni at free-electrons.com
Mon Mar 9 00:55:46 PDT 2015


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

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