PCI/ACPI: Always resume devices on ACPI wakeup notifications

It turns out that the _Lxx control methods provided by some BIOSes
clear the PME Status bit of PCI devices they handle, which means that
pci_acpi_wake_dev() cannot really use that bit to check whether or
not the device has signalled wakeup.

One symptom of the problem is, for example, that when an affected PCI
USB controller is runtime-suspended, then plugging in a new USB device
into one of the controller's ports will not wake up the controller,
which should happen.

For this reason, make pci_acpi_wake_dev() always attempt to resume
the device it is called for regardless of the device's PME Status bit
value (that bit still has to be cleared if set at this point,
though).
Reported-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Matthew Garrett <mjg59@srcf.ucam.org>
CC: stable@vger.kernel.org	# v3.7+

drivers/pci/pci-acpi.c

@@ -53,14 +53,15 @@ static void pci_acpi_wake_dev(acpi_handle handle, u32 event, void *context)
 		return;
 	}
 
-	if (!pci_dev->pm_cap || !pci_dev->pme_support
-	     || pci_check_pme_status(pci_dev)) {
+	/* Clear PME Status if set. */
+	if (pci_dev->pme_support)
+		pci_check_pme_status(pci_dev);
+
 	if (pci_dev->pme_poll)
 		pci_dev->pme_poll = false;
 
 	pci_wakeup_event(pci_dev);
 	pm_runtime_resume(&pci_dev->dev);
-	}
 
 	if (pci_dev->subordinate)
 		pci_pme_wakeup_bus(pci_dev->subordinate);