3 files changed, 23 insertions, 10 deletions

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 20f423337e1f..e9304dc7ebfa 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -169,9 +169,7 @@ int acpi_create_platform_device(struct acpi_device *adev,
                                         Video
   -------------------------------------------------------------------------- */
 #if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE)
-bool acpi_video_backlight_quirks(void);
-#else
-static inline bool acpi_video_backlight_quirks(void) { return false; }
+bool acpi_osi_is_win8(void);
 #endif
 
 #endif /* _ACPI_INTERNAL_H_ */
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 3bd1eaa4ef90..d020df5a732a 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -88,6 +88,13 @@ module_param(allow_duplicates, bool, 0644);
 static bool use_bios_initial_backlight = 1;
 module_param(use_bios_initial_backlight, bool, 0644);
 
+/*
+ * For Windows 8 systems: if set ture and the GPU driver has
+ * registered a backlight interface, skip registering ACPI video's.
+ */
+static bool use_native_backlight = false;
+module_param(use_native_backlight, bool, 0644);
+
 static int register_count;
 static struct mutex video_list_lock;
 static struct list_head video_bus_head;
@@ -232,6 +239,14 @@ static int acpi_video_get_next_level(struct acpi_video_device *device,
 static int acpi_video_switch_brightness(struct acpi_video_device *device,
                                          int event);
 
+static bool acpi_video_verify_backlight_support(void)
+{
+        if (acpi_osi_is_win8() && use_native_backlight &&
+            backlight_device_registered(BACKLIGHT_RAW))
+                return false;
+        return acpi_video_backlight_support();
+}
+
 /* backlight device sysfs support */
 static int acpi_video_get_brightness(struct backlight_device *bd)
 {
@@ -1256,8 +1271,8 @@ acpi_video_switch_brightness(struct acpi_video_device *device, int event)
         unsigned long long level_current, level_next;
         int result = -EINVAL;
 
-        /* no warning message if acpi_backlight=vendor is used */
-        if (!acpi_video_backlight_support())
+        /* no warning message if acpi_backlight=vendor or a quirk is used */
+        if (!acpi_video_verify_backlight_support())
                 return 0;
 
         if (!device->brightness)
@@ -1386,13 +1401,13 @@ acpi_video_bus_get_devices(struct acpi_video_bus *video,
 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
 {
         return acpi_video_bus_DOS(video, 0,
-                                  acpi_video_backlight_quirks() ? 1 : 0);
+                                  acpi_osi_is_win8() ? 1 : 0);
 }
 
 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
 {
         return acpi_video_bus_DOS(video, 0,
-                                  acpi_video_backlight_quirks() ? 0 : 1);
+                                  acpi_osi_is_win8() ? 0 : 1);
 }
 
 static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
@@ -1558,7 +1573,7 @@ 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_backlight_support()) {
+        if (acpi_video_verify_backlight_support()) {
                 struct backlight_properties props;
                 struct pci_dev *pdev;
                 acpi_handle acpi_parent;
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 940edbf2fe8f..b6399343de51 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -233,11 +233,11 @@ static void acpi_video_caps_check(void)
                 acpi_video_get_capabilities(NULL);
 }
 
-bool acpi_video_backlight_quirks(void)
+bool acpi_osi_is_win8(void)
 {
         return acpi_gbl_osi_data >= ACPI_OSI_WIN_8;
 }
-EXPORT_SYMBOL(acpi_video_backlight_quirks);
+EXPORT_SYMBOL(acpi_osi_is_win8);
 
 /* Promote the vendor interface instead of the generic video module.
  * This function allow DMI blacklists to be implemented by externals