I also have this problem. I am using Ubuntu 14.04 64 bit with a Thinkpad T440S.
At the beginning, I have the following four problems: 1. After every boot, the brightness is set to maximum. 2. The brightness can't be adjusted smoothly. Only 4 brightnesses can be achieved with Fn keys. 3. After recovering from dimming, the brightness is set to maximum. 4. The following error message is printed during the boot: [ 12.843633] thinkpad_acpi: Unsupported brightness interface, please contact ibm-acpi-de...@lists.sourceforge.net The following workaround fixes 1 for me. http://askubuntu.com/questions/151651/brightness-is-reset-to-maximum-on-every-restart I add "acpi_backlight=vendor" kernel parameter according to https://wiki.ubuntu.com/Kernel/Debugging/Backlight. This fixes 2 and 3 for me. But 4 still exists. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1320659 Title: [Lenovo ThinkPad Edge E430] "thinkpad unsupported brightness interface" message is showing while booting up To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1320659/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
