Since I can't correct my typo, I add my comment one more time. With the use of v3.18-rc3-vivid, the following problems still exist:
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 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1388817 Title: Backlight brightness problem with Thinkpad T440S To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388817/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs