I'm on a Dell XPS 15z. I detail below other attempts (all pretty much taken from this thread but unsuccessful for my setup); instead, what works for me is to (1) change in /etc/default/grub the variable GRUB_CMDLINE_LINUX_DEFAULT to "acpi_backlight=vendor dell_laptop.backlight=0 quiet splash", i.e., adding the entire part beginning "acpi_backlight..." ahead of "quiet splash", as suggested in
https://wiki.ubuntu.com/HardwareSupport/Machines/Laptops/Dell/XPS/15z (thanks). What also worked was (2) replace the Display Manager lightdm with gdm, i.e., in a terminal do sudo apt-get install gdm and then select gdm, although obviously that's not a fix for a lightdm problem. [Alternatively, "sudo dpkg-reconfigure gdm" if you're, luckily, already running lightdm or some other DM.] Trials that failed for me: A. In /etc/init/lighdm.conf Add line "sleep 10" just before line "exec lightdm" Add flag "-d" to "exec lightdm" Add line "and stopped udevtrigger" just after line "and started dbus" Add line "respawn" right before "emits login-session start" (whether in combination or singly). B. In a terminal "sudo restart lightdm" or "sudo service lightdm restart" or "sudo service lightdm --full-restart". -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/969489 Title: lightdm tries (and fails) to start too early? Status in Upstart: New Status in “lightdm” package in Ubuntu: Confirmed Bug description: Sometimes lightdm comes up fine. Other times it appears to fail. x-0.log shows it tried to load 'nv' (rather than 'nvidia' which is what actually exists). When I then log into console and 'start lightdm', it comes up fine (on :1). I've not had it come up ok today, so I don't know if, when it comes up fine, it starts on :0. No idea if the lightdm.conf needs a change to 'start on'clause, or if this is just a case of a bad shipped config file (for module 'nv'). ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: lightdm 1.1.9-0ubuntu1 ProcVersionSignature: Ubuntu 3.2.0-20.33-generic 3.2.12 Uname: Linux 3.2.0-20-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.0-0ubuntu1 Architecture: amd64 Date: Fri Mar 30 13:40:27 2012 InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120323) ProcEnviron: TERM=xterm PATH=(custom, user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: lightdm UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/upstart/+bug/969489/+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
