Windows 8 introduced new policy for backlight control by pushing it out to graphics drivers. This appears to have coincided with a range of vendors adding Windows 8 checks to their backlight control code which trigger either awkward behaviour (Lenovo) or complete brokenness (some Dells). The simplest thing to do would be to just disable ACPI backlight control entirely if the firmware indicates Windows 8 support, but it's entirely possible that individual graphics drivers might still make use of the ACPI functionality in preference to native control. The first two patches in this series are picked from other patchesets aimed at solving similar problems. The last simply unregisters ACPI backlight control on Windows 8 systems when using an Intel GPU. Similar code could be added to other drivers, but I'm reluctant to do so without further investigation as to the behaviour of the vendor drivers under Windows. -- Matthew Garrett | mjg59@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
