I've double check this issue with different kernel parameters, by adding following parameter, the brightness keys and the dim_brightness test now works fine, even OSD can response correctly.
acpi_osi='!Windows 2012' but this is still an issue, since changing parameters in /etc/default/grub will not pass the certification test. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1270079 Title: [Lenovo T540p, W540] Backlight interfaces not fully working To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1270079/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
