On Friday, June 17, 2011, Alan Stern wrote: > On Fri, 17 Jun 2011, Rafael J. Wysocki wrote: > > > Having considered that a bit more I see that, in fact, commit > > e8665002477f0278f84f898145b1f141ba26ee26 (PM: Allow pm_runtime_suspend() to > > succeed during system suspend) has introduced at least one regression. > > Namely, the PCI bus type runs pm_runtime_resume() in its .prepare() > > callback to guarantee that devices will be in a well known state before > > the PCI .suspend() and .suspend_noirq() callbacks are executed. > > Unfortunately, after commit e8665002477f0278f84f898145b1f141ba26ee26 this > > isn't valid any more, because devices can be runtime-suspend after the > > pm_runtime_resume() in .prepare() has run. > > > > USB seems to do something similar in choose_wakeup(). > > > > So, either the both of these subsystems should be modified to use > > pm_runtime_get_sync() and then pm_runtime_put_<something>() some time > > during resume, or we should revert commit e8665002477f0278f84f898145b1f141ba26ee26. > > pm_runtime_put_noidle would be appropriate. > > > Quite frankly, which shouldn't be a surprise to anyone at this point, I'd > > prefer to revert that commit for 3.0. > > Maybe we can compromise. Instead of reverting that commit outright, > put the get_noresume just before the suspend callback and put the > put_sync just after the resume callback. That wouldn't fix the PCI problem, though, because it would leave a small window in which the device could be suspended after the pm_runtime_resume() in pci_pm_prepare() had run. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
