On Thursday 20 August 2009, Alan Stern wrote: > On Thu, 20 Aug 2009, Rafael J. Wysocki wrote: > > > On Thursday 20 August 2009, Alan Stern wrote: > > > On Thu, 20 Aug 2009, Matthew Garrett wrote: > > > > > > > > If the wakeup signal isn't squelched at the source, as part of the > > > > > event handling, will we get an interrupt storm? Will the uhci-hcd > > > > > resume routine be able to handle this or does it need to be done > > > > > earlier? In other words, do we need special-purpose code in the PCI > > > > > layer to handler it? > > > > > > > > No, nothing special needs to be done at the PCI level. It seems that > > > > (for Intel at least) there's no need to do anything special at the UHCI > > > > level either. > > > > > > This contradicts what Shaohua wrote: > > > > > > "The only case is UHCI in my mind. Because UHCI has non-standard wakeup > > > event register. If BIOS doesn't handle it correctly (for example, not > > > clear the wakeup event after a GPE), we will keep see the wakeup > > > event." > > > > I'm not sure what the phrase "we will keep see the wakeup event" is supposed to > > mean. For us to "see" any events there has to be a GPE set up or PCIe PME > > enabled on the right root port. Otherwise I don't see how we can receive the > > event at all. > > > > The bus type wakeup code won't know how to clear the register to acknowledge > > the wakeup, but the driver's ->runtime_resume() callback surely can do that. > > > > > What code would be responsible for setting and clearing the > > > non-standard wakeup register? Are you assuming that ACPI will always > > > handle it? I guess that's a reasonable assumption -- if ACPI wasn't > > > aware of the register then it never would get enabled, and conversely, > > > if ACPI was aware and could enable the register, then ACPI ought to > > > disable it when necessary. > > > > In any case the event has to be raised in one of the standard ways. > > I'm still not clear on this. Does the non-standard wakeup register > have to be set and cleared by the suspend and resume routines in > uhci-hcd, or will it be handled by other code? I'm not sure if anyone can answer this 100% accurately without doing any testing. Best, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
