Acer-WMI: fingers off backlight if video.ko is serving this functionality

Signed-off-by: NThomas Renninger <trenn@suse.de>
Acked-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NCarlos Corbacho <carlos@strangeworlds.co.uk>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/misc/acer-wmi.c

@@ -1297,6 +1297,12 @@ static int __init acer_wmi_init(void)
 
 	set_quirks();
 
+	if (!acpi_video_backlight_support() && has_cap(ACER_CAP_BRIGHTNESS)) {
+		interface->capability &= ~ACER_CAP_BRIGHTNESS;
+		printk(ACER_INFO "Brightness must be controlled by "
+		       "generic video driver\n");
+	}
+
 	if (platform_driver_register(&acer_platform_driver)) {
 		printk(ACER_ERR "Unable to register platform driver.\n");
 		goto error_platform_register;