On Friday 16 January 2009, Alan Stern wrote: > On Fri, 16 Jan 2009, Rafael J. Wysocki wrote: > > > There is a problem in our handling of suspend-resume of PCI devices > > that many of them have their standard config registers restored with > > interrupts enabled and they are put into the full power state with > > interrupts enabled as well. This may lead to the following scenario: > > * an interrupt vector is shared between two or more devices > > * one device is resumed earlier and generates an interrupt > > * the interrupt handler of another device tries to handle it and > > attempts to access the device the config space of which hasn't > > been restored yet and/or which still is in a low power state > > * the system crashes as a result > > > > To prevent this from happening we should restore the standard > > configuration registers of all devices with interrupts disabled and > > we should put them into the D0 power state right after that. > > Unfortunately, this cannot be done using the existing > > pci_set_power_state(), because it can sleep. Also, to do it we have > > to make sure that the config spaces of all devices were actually > > saved during suspend. > > Alternatively, PCI drivers should be smart enough to realize that a > shared interrupt arriving while their device is suspended could not > possibly be generated by that device. In such a case the driver can > return IRQ_NONE directly, without ever touching the device. > > USB does this. However I admit that fixing every PCI driver would be a > big chore... Well, that's the point. :-) Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
