> 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, Fabio -- Fabio Baltieri -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
