sony-laptop: fingers off backlight if video.ko is serving this functi…

…onality

Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/sony-laptop.c

@@ -1038,7 +1038,11 @@ static int sony_nc_add(struct acpi_device *device)
 		goto outinput;
 	}
 
-	if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle, "GBRT", &handle))) {
+	if (!acpi_video_backlight_support()) {
+		printk(KERN_INFO DRV_PFX "Sony: Brightness ignored, must be "
+		       "controlled by ACPI video driver\n");
+	} else if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle, "GBRT",
+						&handle))) {
 		sony_backlight_device = backlight_device_register("sony", NULL,
 								  NULL,
 								  &sony_backlight_ops);