ACPI DSDT has actually two paths for changing backlight. One is simple to understand and is using SMI Command Port B2, but only works when booting with BIOS. The other is quite complicated (for me acpi noob) and is using a ressource called "smbus-ddcblc". I don't know if the backlight acpi is failing because it doesn't follow the right code path (in which case acpi think it's bios where it isn't) or because memory is not mapped as acpi thinks it should be, or... ?
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-power-manager in Ubuntu. https://bugs.launchpad.net/bugs/818826 Title: backlight brightness control won't work in 2011 iMac 27" Status in “gnome-power-manager” package in Ubuntu: Confirmed Bug description: When I press the 'Brightness Control(UP, DOWN)' key in Apple Keyboard, the OSD shows Increasing Backlight(or Decrease) at the right-top corner. But the Screen Brightness doesn't changed. Also, I waited 15 minutes, the screen turned black. (Power Setting) But the Backlight still alive. This iMac has AMD Radeon HD 6970M. I think maybe it's because the driver doesn't exist in kernel module. Sorry about my poor English and few information. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/818826/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
