PCI PM: Introduce device flag wakeup_prepared

Introduce a new PCI device flag, wakeup_prepared, to prevent PCI
wake-up preparation code from being executed twice in a row for the
same device and for the same purpose.

Reviewed-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.c

@@ -1225,6 +1225,10 @@ int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
 	if (enable && !device_may_wakeup(&dev->dev))
 		return -EINVAL;
 
+	/* Don't do the same thing twice in a row for one device. */
+	if (!!enable == !!dev->wakeup_prepared)
+		return 0;
+
 	/*
 	 * According to "PCI System Architecture" 4th ed. by Tom Shanley & Don
 	 * Anderson we should be doing PME# wake enable followed by ACPI wake
@@ -1241,9 +1245,12 @@ int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable)
 		error = platform_pci_sleep_wake(dev, true);
 		if (ret)
 			ret = error;
+		if (!ret)
+			dev->wakeup_prepared = true;
 	} else {
 		platform_pci_sleep_wake(dev, false);
 		pci_pme_active(dev, false);
+		dev->wakeup_prepared = false;
 	}
 
 	return ret;
@@ -1365,6 +1372,7 @@ void pci_pm_init(struct pci_dev *dev)
 	int pm;
 	u16 pmc;
 
+	dev->wakeup_prepared = false;
 	dev->pm_cap = 0;
 
 	/* find PCI PM capability in list */

include/linux/pci.h

@@ -241,6 +241,7 @@ struct pci_dev {
 	unsigned int	d1_support:1;	/* Low power state D1 is supported */
 	unsigned int	d2_support:1;	/* Low power state D2 is supported */
 	unsigned int	no_d1d2:1;	/* Only allow D0 and D3 */
+	unsigned int	wakeup_prepared:1;
 
 #ifdef CONFIG_PCIEASPM
 	struct pcie_link_state	*link_state;	/* ASPM link state. */