PCI: Check for PME in targeted sleep state

One some systems, the firmware does not allow certain PCI devices to be put
in deep D-states.  This can cause problems for wakeup signalling, if the
device does not support PME# in the deepest allowed suspend state.  For
example, Pierre reports that on his system, ACPI does not permit his xHCI
host controller to go into D3 during runtime suspend -- but D3 is the only
state in which the controller can generate PME# signals.  As a result, the
controller goes into runtime suspend but never wakes up, so it doesn't work
properly.  USB devices plugged into the controller are never detected.

If the device relies on PME# for wakeup signals but is not capable of
generating PME# in the target state, the PCI core should accurately report
that it cannot do wakeup from runtime suspend.  This patch modifies the
pci_dev_run_wake() routine to add this check.

Reported-by: Pierre de Villemereuil <[email protected]>
Tested-by: Pierre de Villemereuil <[email protected]>
Signed-off-by: Alan Stern <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
CC: [email protected]
CC: Lukas Wunner <[email protected]>

drivers/pci/pci.c

@@ -2106,6 +2106,10 @@ bool pci_dev_run_wake(struct pci_dev *dev)
 	if (!dev->pme_support)
 		return false;
 
+	/* PME-capable in principle, but not from the intended sleep state */
+	if (!pci_pme_capable(dev, pci_target_state(dev)))
+		return false;
+
 	while (bus->parent) {
 		struct pci_dev *bridge = bus->self;