The addition of "Windows 2012" to the OSI strings in the 3.7 cycle has caused backlight brightness adjustment to break on my ThinkPad T530. Without "Windows 2012" _BCL returns the actual 16 brightness levels: 5, 10, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100 When "Windows 2012" is present, it returns 101 levels 0-100, but _BCM rounds any value up to one of the real values above. This interacts badly with gnome-settings-daemon, which attempts to change brightness in increments of 5 (1/20 of 100). If brightness is currently 100, it attempts to decrement it to 95, but it gets rounded back up to 100, so it's impossible to decrease the brightness. Booting with acpi_osi="!Windows 2012" fixes the problem, though I'm not sure if it introduces others; I see several other things depend on WIN8 in DSDT. Perhaps this should be fixed in gnome-settings-daemon, but since it appears on the surface to be a kernel regression (3.6 works, 3.7 broken) I thought I'd report it here first. ThinkPad T530, BIOS 2.07, booting with pure UEFI (BIOS compatibility module disabled). I can provide all or part of acpidump output if needed. -Ben Not subscribed, please copy me on replies. -- 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
