ACPI / hotplug / PCI: Use _OST to notify firmware about notify status

The spec suggests that we should use _OST to notify the platform
about the status of notifications it sends us, for example so that
it doesn't repeate a notification that has been handled already.

This turns out to help reduce the amount of diagnostic output from
the ACPIPHP subsystem and speed up boot on at least one system that
generates multiple device check notifies for PCIe devices on the root
bus during boot.

Reported-and-tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/hotplug/acpiphp_glue.c

@@ -870,6 +870,8 @@ static void hotplug_event_work(struct work_struct *work)
 	hotplug_event(hp_work->handle, hp_work->type, context);
 
 	acpi_scan_lock_release();
+	acpi_evaluate_hotplug_ost(hp_work->handle, hp_work->type,
+				  ACPI_OST_SC_SUCCESS, NULL);
 	kfree(hp_work); /* allocated in handle_hotplug_event() */
 	put_bridge(context->func.parent);
 }
@@ -885,11 +887,15 @@ static void hotplug_event_work(struct work_struct *work)
 static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 {
 	struct acpiphp_context *context;
+	u32 ost_code = ACPI_OST_SC_SUCCESS;
 
 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 	case ACPI_NOTIFY_DEVICE_CHECK:
+		break;
 	case ACPI_NOTIFY_EJECT_REQUEST:
+		ost_code = ACPI_OST_SC_EJECT_IN_PROGRESS;
+		acpi_evaluate_hotplug_ost(handle, type, ost_code, NULL);
 		break;
 
 	case ACPI_NOTIFY_DEVICE_WAKE:
@@ -898,20 +904,21 @@ static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 	case ACPI_NOTIFY_FREQUENCY_MISMATCH:
 		acpi_handle_err(handle, "Device cannot be configured due "
 				"to a frequency mismatch\n");
-		return;
+		goto out;
 
 	case ACPI_NOTIFY_BUS_MODE_MISMATCH:
 		acpi_handle_err(handle, "Device cannot be configured due "
 				"to a bus mode mismatch\n");
-		return;
+		goto out;
 
 	case ACPI_NOTIFY_POWER_FAULT:
 		acpi_handle_err(handle, "Device has suffered a power fault\n");
-		return;
+		goto out;
 
 	default:
 		acpi_handle_warn(handle, "Unsupported event type 0x%x\n", type);
-		return;
+		ost_code = ACPI_OST_SC_UNRECOGNIZED_NOTIFY;
+		goto out;
 	}
 
 	mutex_lock(&acpiphp_context_lock);
@@ -920,8 +927,14 @@ static void handle_hotplug_event(acpi_handle handle, u32 type, void *data)
 		get_bridge(context->func.parent);
 		acpiphp_put_context(context);
 		alloc_acpi_hp_work(handle, type, context, hotplug_event_work);
+		mutex_unlock(&acpiphp_context_lock);
+		return;
 	}
 	mutex_unlock(&acpiphp_context_lock);
+	ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
+
+ out:
+	acpi_evaluate_hotplug_ost(handle, type, ost_code, NULL);
 }
 
 /*