Rafael, Alexandre, On Wed, 11 Mar 2015 02:03:08 +0100 "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> wrote: > On Tuesday, March 10, 2015 11:33:05 PM Alexandre Belloni wrote: > > On 10/03/2015 at 23:31:52 +0100, Rafael J. Wysocki wrote : > > > 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 didn't exactly look in details but apart from the wakeup from gpio > > handling (keeping the pio controller clocked in the case one of its gpio > > has wakeup enabled), I don't think it does much more. It uses > > irq_gc_set_wake(). > > Well, that only modifies gc->wake_active, so no hardware interactions. I'm not sure I understand the whole discussion, but calling enable_irq_wake() does affect suspend behavior on at91 platforms. Take a look at the suspend() implementation [1], it's making use of the wake_active field (modified by irq_gc_set_wake) when entering suspend in order to keep wakeup IRQ sources enabled. Best Regards, Boris [1]http://lxr.free-electrons.com/source/drivers/irqchip/irq-atmel-aic.c#L106 -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
