On Saturday 07 March 2009, Alan Stern wrote: > On Sat, 7 Mar 2009, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rjw@xxxxxxx> > > > > Introduce two helper functions allowing us to prevent device drivers > > from getting any interrupts (without disabling interrupts on the CPU) > > during suspend (or hibernation) and to make them start to receive > > interrupts again during the subsequent resume, respectively. These > > functions make it possible to keep timer interrupts enabled while the > > "late" suspend and "early" resume callbacks provided by device > > drivers are being executed. > > > > Use these functions to rework the handling of interrupts during > > suspend (hibernation) and resume. Namely, interrupts will only be > > disabled on the CPU right before suspending sysdevs, while device > > drivers will be prevented from receiving interrupts, with the help of > > the new helper function, before their "late" suspend callbacks run > > (and analogously during resume). > > > > In addition, since the device interrups are now disabled before the > > CPU has turned all interrupts off and the CPU will ACK the interrupts > > setting the IRQ_PENDING bit for them, check in sysdev_suspend() if > > any wake-up interrupts are pending and abort suspend if that's the > > case. > > One thing about this isn't clear: the distinction between "wake-up" > interrupts and other interrupts. > > In an ideal world, the only pending interrupts during sysdev_suspend > would be wake-up interrupts, because drivers would have prevented their > devices from generating any other kind of IRQ and would have done all > the necessary synchronization as part of their suspend (_not_ > suspend_late) methods. Thus there would be no need to distinguish > between wake-up and non-wake-up interrupts. > > So perhaps you're worried about drivers that aren't sufficiently > clever. Or is something deeper going on? Some drivers leave interrupts enabled during suspend on purpose and mark them as "wake-up interrupts" so that the platform can abort suspend if any of them is pending at the time the "enter suspend" hook is called (this doesn't happen on x86 AFAICS). However, after the $subject patch the CPU will ACK those interrupts if they happen between suspend_device_irqs() and local_irq_disable(), so the platform won't see them as pending. Instead, they will have IRQ_PENDING set in desc->status, so we check if this is the case. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
