A "regression in the intel driver" doesn't seem to explain why this was not an issue in a gnome session, nor to the fact that - xset dpms force off xset dpms force on returned display both in greeter & session (and nvidia driver loaded & worked fine, with or without a visible display.
you 'fixed' the issue but maybe not for the correct reason -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1507676 Title: Nvidia-Prime not switching from intel to nvidia leading to a black screen Status in ubuntu-drivers-common package in Ubuntu: Fix Released Status in xserver-xorg-video-intel package in Ubuntu: In Progress Bug description: STEPS: 1. Install 15.10 on a laptop that supports optimus nvidia/intel hybrid graphics 2. Install nvidia and nvidia-prime 3. Open nvidia settings 4. Switch to nvidia 5. Log out 6. Hear the login drums EXPECTED: I expect to see the lightdm login page ACTUAL: You are presented with a black page TEMP WORKAROUND: 1. Tap ctrl-alt-f1 2. login 3. run sudo prime-select intel 4. run sudo service lightdm restart 5. System is back running on the intel stack alone. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubuntu-drivers-common/+bug/1507676/+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

