On Thu, Mar 5, 2015 at 11:57 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > [...] > >> > > err = request_irq(wdt->irq, wdt_interrupt, >> > > - IRQF_SHARED | IRQF_IRQPOLL, >> > > + IRQF_SHARED | IRQF_IRQPOLL | >> > > + IRQF_NO_SUSPEND, >> > >> > I'm a little confused by this. What happens if the watchdog fires when >> > we're actually in the suspended state (when IRQF_NO_SUSPEND interrupts >> > aren't guaranteed to be delivered). >> >> Why wouldn't they be delivered? >> >> If that's suspend-to-idle, we'll handle them normally. If that's full suspend, >> they may not be handled at the last stage (when we run on one CPU with interrupts >> off), but that was the case before the wakeup interrupts rework already and I'd >> expect it to be taken into account somehow in the existing code (or if it isn't >> taken into account, we have a bug, but it is not related to this series). > > There's no enable_irq_wake(wdt->irq), and I was under the impression this > is for full suspend. enable_irq_wake() has no effect on IRQF_NO_SUSPEND interrupts, so if the driver uses IRQF_NO_SUSPEND, it does not need to use enable_irq_wake() in addition to that. Drivers using IRQF_COND_SUSPEND generally should use enable_irq_wake() too in case they end up in a situation without sharing a NO_SUSPEND interrupt, in which case their interrupt handlers won't be called after suspend_device_irqs(), so they need to rely on the core to do the wakeup. > I agree that if problematic, it's an existing bug. Given Boris's > comments in the other thread this may just a minor semantic issue w.r.t. > IRQF_NO_SUSPEND vs IRQF_COND_SUSPEND. It depends on whether or not the watchdog's interrupt handler has to be called immediately after receiving an interrupt (IRQF_NO_SUSPEND is better then) or it can be deferred till the resume_device_irqs() time. Rafael -- 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
