dell-wmi: do not keep driver loaded on unsupported boxes

There is no point in having the driver loaded in memory if we fail
to locate particular WMI GUID.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/platform/x86/dell-wmi.c

@@ -325,11 +325,14 @@ static int __init dell_wmi_init(void)
 	int err;
 
 	if (wmi_has_guid(DELL_EVENT_GUID)) {
+		printk(KERN_WARNING "dell-wmi: No known WMI GUID found\n");
+		return -ENODEV;
+	}
 
 	dmi_walk(find_hk_type, NULL);
+	acpi_video = acpi_video_backlight_support();
 
 	err = dell_wmi_input_setup();
-
 	if (err)
 		return err;
 
@@ -337,25 +340,19 @@ static int __init dell_wmi_init(void)
 					 dell_wmi_notify, NULL);
 	if (err) {
 		input_unregister_device(dell_wmi_input_dev);
-			printk(KERN_ERR "dell-wmi: Unable to register"
-			       " notify handler - %d\n", err);
+		printk(KERN_ERR
+			"dell-wmi: Unable to register notify handler - %d\n",
+			err);
 		return err;
 	}
 
-		acpi_video = acpi_video_backlight_support();
-
-	} else
-		printk(KERN_WARNING "dell-wmi: No known WMI GUID found\n");
-
 	return 0;
 }
 
 static void __exit dell_wmi_exit(void)
 {
-	if (wmi_has_guid(DELL_EVENT_GUID)) {
 	wmi_remove_notify_handler(DELL_EVENT_GUID);
 	input_unregister_device(dell_wmi_input_dev);
-	}
 }
 
 module_init(dell_wmi_init);