Merge back earlier 'acpi-video' material.

Documentation/kernel-parameters.txt

@@ -3461,7 +3461,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			the allocated input device; If set to 0, video driver
 			will only send out the event without touching backlight
 			brightness level.
-			default: 1
+			default: 0
 
 	virtio_mmio.device=
 			[VMMIO] Memory mapped virtio (platform) device.

drivers/acpi/video.c

@@ -68,7 +68,7 @@ MODULE_AUTHOR("Bruno Ducrot");
 MODULE_DESCRIPTION("ACPI Video Driver");
 MODULE_LICENSE("GPL");
 
-static bool brightness_switch_enabled = 1;
+static bool brightness_switch_enabled;
 module_param(brightness_switch_enabled, bool, 0644);
 
 /*
@@ -150,6 +150,7 @@ struct acpi_video_enumerated_device {
 
 struct acpi_video_bus {
 	struct acpi_device *device;
+	bool backlight_registered;
 	u8 dos_setting;
 	struct acpi_video_enumerated_device *attached_array;
 	u8 attached_count;
@@ -1658,7 +1659,6 @@ acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
 
 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
 {
-	if (acpi_video_verify_backlight_support()) {
 	struct backlight_properties props;
 	struct pci_dev *pdev;
 	acpi_handle acpi_parent;
@@ -1706,11 +1706,9 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
 				device->dev, &video_cooling_ops);
 	if (IS_ERR(device->cooling_dev)) {
 		/*
-			 * Set cooling_dev to NULL so we don't crash trying to
-			 * free it.
-			 * Also, why the hell we are returning early and
-			 * not attempt to register video output if cooling
-			 * device registration failed?
+		 * Set cooling_dev to NULL so we don't crash trying to free it.
+		 * Also, why the hell we are returning early and not attempt to
+		 * register video output if cooling device registration failed?
 		 * -- dtor
 		 */
 		device->cooling_dev = NULL;
@@ -1728,18 +1726,22 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
 			&device->dev->dev.kobj, "device");
 	if (result)
 		printk(KERN_ERR PREFIX "Create sysfs link\n");
-	}
 }
 
 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
 {
 	struct acpi_video_device *dev;
 
+	if (!acpi_video_verify_backlight_support())
+		return 0;
+
 	mutex_lock(&video->device_list_lock);
 	list_for_each_entry(dev, &video->video_device_list, entry)
 		acpi_video_dev_register_backlight(dev);
 	mutex_unlock(&video->device_list_lock);
 
+	video->backlight_registered = true;
+
 	video->pm_nb.notifier_call = acpi_video_resume;
 	video->pm_nb.priority = 0;
 	return register_pm_notifier(&video->pm_nb);
@@ -1767,13 +1769,20 @@ static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device
 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
 {
 	struct acpi_video_device *dev;
-	int error = unregister_pm_notifier(&video->pm_nb);
+	int error;
+
+	if (!video->backlight_registered)
+		return 0;
+
+	error = unregister_pm_notifier(&video->pm_nb);
 
 	mutex_lock(&video->device_list_lock);
 	list_for_each_entry(dev, &video->video_device_list, entry)
 		acpi_video_dev_unregister_backlight(dev);
 	mutex_unlock(&video->device_list_lock);
 
+	video->backlight_registered = false;
+
 	return error;
 }
 
@@ -2061,6 +2070,20 @@ void acpi_video_unregister(void)
 }
 EXPORT_SYMBOL(acpi_video_unregister);
 
+void acpi_video_unregister_backlight(void)
+{
+	struct acpi_video_bus *video;
+
+	if (!register_count)
+		return;
+
+	mutex_lock(&video_list_lock);
+	list_for_each_entry(video, &video_bus_head, entry)
+		acpi_video_bus_unregister_backlight(video);
+	mutex_unlock(&video_list_lock);
+}
+EXPORT_SYMBOL(acpi_video_unregister_backlight);
+
 /*
  * This is kind of nasty. Hardware using Intel chipsets may require
  * the video opregion code to be run first in order to initialise

drivers/platform/x86/acer-wmi.c

@@ -570,6 +570,14 @@ static const struct dmi_system_id video_vendor_dmi_table[] = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5750"),
 		},
 	},
+	{
+		.callback = video_set_backlight_video_vendor,
+		.ident = "Acer Aspire 5741",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5741"),
+		},
+	},
 	{}
 };
 
@@ -2228,7 +2236,7 @@ static int __init acer_wmi_init(void)
 		pr_info("Brightness must be controlled by acpi video driver\n");
 	} else {
 		pr_info("Disabling ACPI video driver\n");
-		acpi_video_unregister();
+		acpi_video_unregister_backlight();
 	}
 
 	if (wmi_has_guid(WMID_GUID3)) {

include/acpi/video.h

@@ -19,11 +19,13 @@ struct acpi_device;
 #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
 extern int acpi_video_register(void);
 extern void acpi_video_unregister(void);
+extern void acpi_video_unregister_backlight(void);
 extern int acpi_video_get_edid(struct acpi_device *device, int type,
 			       int device_id, void **edid);
 #else
 static inline int acpi_video_register(void) { return 0; }
 static inline void acpi_video_unregister(void) { return; }
+static inline void acpi_video_unregister_backlight(void) { return; }
 static inline int acpi_video_get_edid(struct acpi_device *device, int type,
 				      int device_id, void **edid)
 {