On Saturday, August 07, 2010, Alan Stern wrote: > On Sat, 7 Aug 2010, Rafael J. Wysocki wrote: > > > > Arguably not every PCI interrupt should be regarded as a wakeup event, so > > > I think we can simply say in the cases when that's necessary the driver should > > > be responsible for using pm_wakeup_event() or pm_stay_awake() / pm_relax() as > > > appropriate. > > > > > > My patch only added it to the bus-level code which covered the PME-based > > > wakeup events that _cannot_ be handled by device drivers. > > In other words, your bus-level changes were a necessary but not > sufficient start. I can buy that. > > > Also please note that it depends a good deal on the definition of a "wakeup > > event". Under the definition used when my patch was being developed, ie. that > > wakeup events are the events that would wake up the system from a sleep state, > > PCI interrupts cannot be wakeup events, unless the given device remains in the > > full power state although the system has been suspended (standard PCI devices > > are not allowed to generate signals except for PME from low-power states). > > Um, what do you mean by "event"? Let's take a concrete example. > Suppose you have a system where you want USB plug or unplug events to > cause a wakeup. This is relevant to the discussion at hand if your USB > host controller is a PCI device. > > By your reckoning, a plug or unplug event that occurs while the system > is asleep would be a wakeup event by definition. And yet you say that > the same plug or unplug event occurring while the controller was at > full power would not count as a wakeup event? And in particular, it > should not prevent the system from suspending before the event can be > fully processed? That doesn't make sense. The same event is the same > event, regardless of the context in which it occurs. If it is treated > as a wakeup event in context then it should be treated as a wakeup > event in other contexts too. In this example the event is not a PCI interrupt itself, which is a consqeuence of the event, but the USB plug-unplug. So, whoever detects the plug-unplug should use pm_stay_awake() or pm_wakeup_event(). That may be an interrupt handler of a PCI USB controller, so if that is the case, the controller driver probably should use one of these functions in its interrupt handler. Still, that by no measn implies that _every_ PCI interrupt should in principle be regarded as a wakeup event. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
