Merge branch 'pci/pm'

- Account for _S0W when deciding whether to put bridges in D3 to avoid
  missing hotplug events (Rafael J. Wysocki)

* pci/pm:
  PCI/ACPI: Account for _S0W of the target bridge in acpi_pci_bridge_d3()

3 files changed, 51 insertions, 14 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 97450f4003cc..f007116a8427 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -484,6 +484,25 @@ void acpi_dev_power_up_children_with_adr(struct acpi_device *adev)
 	acpi_dev_for_each_child(adev, acpi_power_up_if_adr_present, NULL);
 }
 
+/**
+ * acpi_dev_power_state_for_wake - Deepest power state for wakeup signaling
+ * @adev: ACPI companion of the target device.
+ *
+ * Evaluate _S0W for @adev and return the value produced by it or return
+ * ACPI_STATE_UNKNOWN on errors (including _S0W not present).
+ */
+u8 acpi_dev_power_state_for_wake(struct acpi_device *adev)
+{
+	unsigned long long state;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state);
+	if (ACPI_FAILURE(status))
+		return ACPI_STATE_UNKNOWN;
+
+	return state;
+}
+
 #ifdef CONFIG_PM
 static DEFINE_MUTEX(acpi_pm_notifier_lock);
 static DEFINE_MUTEX(acpi_pm_notifier_install_lock);
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 068d6745bf98..052a611081ec 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -976,24 +976,41 @@ bool acpi_pci_power_manageable(struct pci_dev *dev)
 bool acpi_pci_bridge_d3(struct pci_dev *dev)
 {
 	struct pci_dev *rpdev;
-	struct acpi_device *adev;
-	acpi_status status;
-	unsigned long long state;
+	struct acpi_device *adev, *rpadev;
 	const union acpi_object *obj;
 
 	if (acpi_pci_disabled || !dev->is_hotplug_bridge)
 		return false;
 
-	/* Assume D3 support if the bridge is power-manageable by ACPI. */
-	if (acpi_pci_power_manageable(dev))
-		return true;
+	adev = ACPI_COMPANION(&dev->dev);
+	if (adev) {
+		/*
+		 * If the bridge has _S0W, whether or not it can go into D3
+		 * depends on what is returned by that object.  In particular,
+		 * if the power state returned by _S0W is D2 or shallower,
+		 * entering D3 should not be allowed.
+		 */
+		if (acpi_dev_power_state_for_wake(adev) <= ACPI_STATE_D2)
+			return false;
+
+		/*
+		 * Otherwise, assume that the bridge can enter D3 so long as it
+		 * is power-manageable via ACPI.
+		 */
+		if (acpi_device_power_manageable(adev))
+			return true;
+	}
 
 	rpdev = pcie_find_root_port(dev);
 	if (!rpdev)
 		return false;
 
-	adev = ACPI_COMPANION(&rpdev->dev);
-	if (!adev)
+	if (rpdev == dev)
+		rpadev = adev;
+	else
+		rpadev = ACPI_COMPANION(&rpdev->dev);
+
+	if (!rpadev)
 		return false;
 
 	/*
@@ -1001,15 +1018,15 @@ bool acpi_pci_bridge_d3(struct pci_dev *dev)
 	 * doesn't supply a wakeup GPE via _PRW, it cannot signal hotplug
 	 * events from low-power states including D3hot and D3cold.
 	 */
-	if (!adev->wakeup.flags.valid)
+	if (!rpadev->wakeup.flags.valid)
 		return false;
 
 	/*
-	 * If the Root Port cannot wake itself from D3hot or D3cold, we
-	 * can't use D3.
+	 * In the bridge-below-a-Root-Port case, evaluate _S0W for the Root Port
+	 * to verify whether or not it can signal wakeup from D3.
 	 */
-	status = acpi_evaluate_integer(adev->handle, "_S0W", NULL, &state);
-	if (ACPI_SUCCESS(status) && state < ACPI_STATE_D3_HOT)
+	if (rpadev != adev &&
+	    acpi_dev_power_state_for_wake(rpadev) <= ACPI_STATE_D2)
 		return false;
 
 	/*
@@ -1018,7 +1035,7 @@ bool acpi_pci_bridge_d3(struct pci_dev *dev)
 	 * bridges *below* that Root Port can also signal hotplug events
 	 * while in D3.
 	 */
-	if (!acpi_dev_get_property(adev, "HotPlugSupportInD3",
+	if (!acpi_dev_get_property(rpadev, "HotPlugSupportInD3",
 				   ACPI_TYPE_INTEGER, &obj) &&
 	    obj->integer.value == 1)
 		return true;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index cd3b75e08ec3..3412297a6b8b 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -533,6 +533,7 @@ int acpi_bus_update_power(acpi_handle handle, int *state_p);
 int acpi_device_update_power(struct acpi_device *device, int *state_p);
 bool acpi_bus_power_manageable(acpi_handle handle);
 void acpi_dev_power_up_children_with_adr(struct acpi_device *adev);
+u8 acpi_dev_power_state_for_wake(struct acpi_device *adev);
 int acpi_device_power_add_dependent(struct acpi_device *adev,
 				    struct device *dev);
 void acpi_device_power_remove_dependent(struct acpi_device *adev,