This is actually a kernel bug where the PWM isn't saved. It affects the specific display type in this machine. It's been fixed upstream already, and was brought into Ubuntu 16.04 (See SRU https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1625932).
The Precision 5510 however ships with Ubuntu 14.04 + vivid HWE stack. The vivid HWE stack does not contain the fix, which is why this issue is happening. ** Also affects: linux (Ubuntu) Importance: Undecided Status: New ** Also affects: xorg (Ubuntu Xenial) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Xenial) Importance: Undecided Status: New ** Also affects: xorg (Ubuntu Vivid) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Vivid) Importance: Undecided Status: New ** Changed in: xorg (Ubuntu Xenial) Status: New => Invalid ** Changed in: xorg (Ubuntu Vivid) Status: New => Incomplete ** Changed in: xorg (Ubuntu Vivid) Status: Incomplete => Invalid ** Changed in: xorg (Ubuntu) Status: Confirmed => Invalid ** Changed in: linux (Ubuntu Xenial) Status: New => Fix Released ** Changed in: linux (Ubuntu) Status: New => Fix Released -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1646537 Title: Backlight sometimes fails to resume from suspend & screen brightness sometimes will not dim below 100% To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1646537/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp