On Saturday, February 23, 2013 03:48:59 PM Fabio Baltieri wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Subject: ACPI / PM: Take unusual configurations of power resources into account > > > > Commit d2e5f0c (ACPI / PCI: Rework the setup and cleanup of device > > wakeup) moved the initial disabling of system wakeup for PCI devices > > into a place where it can actually work and that exposed a hidden old > > issue with crap^Wunusual system designs where the same power > > resources are used for both wakeup power and device power control at > > run time. > > > > Namely, say there is one power resource such that the ACPI power > > state D0 of a PCI device depends on that power resource (i.e. the > > device is in D0 when that power resource is "on") and it is used > > as a wakeup power resource for the same device. Then, calling > > acpi_pci_sleep_wake(pci_dev, false) for the device in question will > > cause the reference counter of that power resource to drop to 0, > > which in turn will cause it to be turned off. As a result, the > > device will go into D3cold at that point, although it should have > > stayed in D0. > > > > As it turns out, that happens to USB controllers on some laptops > > and USB becomes unusable on those machines as a result, which is > > a major regression from v3.8. > > > > To fix this problem, (1) increment the reference counters of wakup > > power resources during their initialization if they are "on" > > initially, (2) prevent acpi_disable_wakeup_device_power() from > > decrementing the reference counters of wakeup power resources that > > were not enabled for wakeup power previously, and (3) prevent > > acpi_enable_wakeup_device_power() from incrementing the reference > > counters of wakeup power resources that already are enabled for > > wakeup power. > > > > In addition to that, if it is impossible to determine the initial > > states of wakeup power resources, avoid enabling wakeup for devices > > whose wakeup power depends on those power resources. > > > > Reported-by: Dave Jones <davej@xxxxxxxxxx> > > Reported-by: Fabio Baltieri <fabio.baltieri@xxxxxxxxxx> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Works just fine! > > Tested-by: Fabio Baltieri <fabio.baltieri@xxxxxxxxxx> Thanks for verifying! Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
