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

Rafael J. Wysocki
2015-03-10T22:08:08Z

On Tuesday, March 10, 2015 10:33:17 PM Alexandre Belloni wrote:
> Hi,
>
> On 09/03/2015 at 15:30:01 +0100, Rafael J. Wysocki wrote :
> > > > > 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.
> >
> > I gather then that the suspend implementation is such that touching the
> > watchdog periodically while suspended is not a problem.
> >
> > Again, can you please tell me how suspend is implemented on at91?
> >
>
> It actually depends on the architecture (at91rm9200, at91sam9 or sama5)
> but basically, the clocks are switched off in almost all the peripheral
> drivers then the ram self refresh activated, the master clock is
> switched off using code running from SRAM and the core is then waiting
> for interrupt.

OK, so it looks like enable_irq_wake() doesn't actually affect the hardware
on those platforms, is that correct?

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.