1 files changed, 35 insertions, 17 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b5b83331da26..2537d86ad634 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -552,8 +552,9 @@ static const struct pci_platform_pm_ops *pci_platform_pm;
 
 int pci_set_platform_pm(const struct pci_platform_pm_ops *ops)
 {
-	if (!ops->is_manageable || !ops->set_state || !ops->choose_state ||
-	    !ops->sleep_wake || !ops->run_wake || !ops->need_resume)
+	if (!ops->is_manageable || !ops->set_state  || !ops->get_state ||
+	    !ops->choose_state  || !ops->sleep_wake || !ops->run_wake  ||
+	    !ops->need_resume)
 		return -EINVAL;
 	pci_platform_pm = ops;
 	return 0;
@@ -570,6 +571,11 @@ static inline int platform_pci_set_power_state(struct pci_dev *dev,
 	return pci_platform_pm ? pci_platform_pm->set_state(dev, t) : -ENOSYS;
 }
 
+static inline pci_power_t platform_pci_get_power_state(struct pci_dev *dev)
+{
+	return pci_platform_pm ? pci_platform_pm->get_state(dev) : PCI_UNKNOWN;
+}
+
 static inline pci_power_t platform_pci_choose_state(struct pci_dev *dev)
 {
 	return pci_platform_pm ?
@@ -701,26 +707,25 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
 }
 
 /**
- * pci_update_current_state - Read PCI power state of given device from its
- *                            PCI PM registers and cache it
+ * pci_update_current_state - Read power state of given device and cache it
  * @dev: PCI device to handle.
  * @state: State to cache in case the device doesn't have the PM capability
+ *
+ * The power state is read from the PMCSR register, which however is
+ * inaccessible in D3cold.  The platform firmware is therefore queried first
+ * to detect accessibility of the register.  In case the platform firmware
+ * reports an incorrect state or the device isn't power manageable by the
+ * platform at all, we try to detect D3cold by testing accessibility of the
+ * vendor ID in config space.
  */
 void pci_update_current_state(struct pci_dev *dev, pci_power_t state)
 {
-	if (dev->pm_cap) {
+	if (platform_pci_get_power_state(dev) == PCI_D3cold ||
+	    !pci_device_is_present(dev)) {
+		dev->current_state = PCI_D3cold;
+	} else if (dev->pm_cap) {
 		u16 pmcsr;
 
-		/*
-		 * Configuration space is not accessible for device in
-		 * D3cold, so just keep or set D3cold for safety
-		 */
-		if (dev->current_state == PCI_D3cold)
-			return;
-		if (state == PCI_D3cold) {
-			dev->current_state = PCI_D3cold;
-			return;
-		}
 		pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
 		dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
 	} else {
@@ -1959,9 +1964,22 @@ static pci_power_t pci_target_state(struct pci_dev *dev)
 		default:
 			target_state = state;
 		}
-	} else if (!dev->pm_cap) {
+
+		return target_state;
+	}
+
+	if (!dev->pm_cap)
 		target_state = PCI_D0;
-	} else if (device_may_wakeup(&dev->dev)) {
+
+	/*
+	 * If the device is in D3cold even though it's not power-manageable by
+	 * the platform, it may have been powered down by non-standard means.
+	 * Best to let it slumber.
+	 */
+	if (dev->current_state == PCI_D3cold)
+		target_state = PCI_D3cold;
+
+	if (device_may_wakeup(&dev->dev)) {
 		/*
 		 * Find the deepest state from which the device can generate
 		 * wake-up events, make it the target state and enable device