PCI PM: Fix handling of devices without drivers

Suspend to RAM is reported to break on some machines as a result of
attempting to put one of driverless PCI devices into a low power
state.  Avoid that by not attepmting to power manage driverless
devices during suspend.

Fix up pci_pm_poweroff() after a previous incomplete fix for the same
thing during hibernation.

This patch is reported to fix the regression from 2.6.28 tracked as
http://bugzilla.kernel.org/show_bug.cgi?id=12605

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-and-tested-by: Eric Sesterhenn <snakebyte@gmx.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci-driver.c

@@ -445,11 +445,11 @@ static void pci_pm_default_suspend_generic(struct pci_dev *pci_dev)
 	pci_save_state(pci_dev);
 }
 
-static void pci_pm_default_suspend(struct pci_dev *pci_dev)
+static void pci_pm_default_suspend(struct pci_dev *pci_dev, bool prepare)
 {
 	pci_pm_default_suspend_generic(pci_dev);
 
-	if (!pci_is_bridge(pci_dev))
+	if (prepare && !pci_is_bridge(pci_dev))
 		pci_prepare_to_sleep(pci_dev);
 
 	pci_fixup_device(pci_fixup_suspend, pci_dev);
@@ -497,19 +497,19 @@ static void pci_pm_complete(struct device *dev)
 static int pci_pm_suspend(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
-	struct device_driver *drv = dev->driver;
+	struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 	int error = 0;
 
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_suspend(dev, PMSG_SUSPEND);
 
-	if (drv && drv->pm && drv->pm->suspend) {
-		error = drv->pm->suspend(dev);
-		suspend_report_result(drv->pm->suspend, error);
+	if (pm && pm->suspend) {
+		error = pm->suspend(dev);
+		suspend_report_result(pm->suspend, error);
 	}
 
 	if (!error)
-		pci_pm_default_suspend(pci_dev);
+		pci_pm_default_suspend(pci_dev, !!pm);
 
 	return error;
 }
@@ -663,22 +663,19 @@ static int pci_pm_thaw(struct device *dev)
 static int pci_pm_poweroff(struct device *dev)
 {
 	struct pci_dev *pci_dev = to_pci_dev(dev);
-	struct device_driver *drv = dev->driver;
+	struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 	int error = 0;
 
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_suspend(dev, PMSG_HIBERNATE);
 
-	if (!drv || !drv->pm)
-		return 0;
-
-	if (drv->pm->poweroff) {
-		error = drv->pm->poweroff(dev);
-		suspend_report_result(drv->pm->poweroff, error);
+	if (pm && pm->poweroff) {
+		error = pm->poweroff(dev);
+		suspend_report_result(pm->poweroff, error);
 	}
 
 	if (!error)
-		pci_pm_default_suspend(pci_dev);
+		pci_pm_default_suspend(pci_dev, !!pm);
 
 	return error;
 }