lightdm-gtk-greeter-team team mailing list archive

[Eddie B <fasteddieb216@xxxxxxxxx>]

I modified lightdm-gtk-greeter to put more debug messages in and found
that the delay starts sometime after lightdm-gtk-greeter closes.  I'm
trying to do the same thing with lightdm to see where the black screen
delay starts, but I'm having trouble getting my modified lightdm to
replace lightdm.

I'm not sure if this is helpful, but I found that if I install light-
locker then the black screen delay also happens when I choose to lock
the screen.  If I uninstall light-locker then only "switch user/unlock"
causes delay and "lock/unlock" displays desktop immediately like stated
in original post.

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https://bugs.launchpad.net/bugs/1865323

Title:
  Switch User+DPMS then click Unlock causes a delay with black screen

Status in lightdm-gtk-greeter package in Ubuntu:
  New

Bug description:
  ed@userver:~$ lsb_release -rd
  Description:	Ubuntu Focal Fossa (development branch)
  Release:	20.04
  ed@userver:~$ apt-cache policy pkgname lightdm-gtk-greeter
  lightdm-gtk-greeter:
    Installed: 2.0.6-0ubuntu1
    Candidate: 2.0.6-0ubuntu1
    Version table:
   *** 2.0.6-0ubuntu1 500
          500 http://us.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
          100 /var/lib/dpkg/status
  N: Unable to locate package pkgname

  I'm not sure if the issue is in the LightDM greeter, but it only
  happens after I use the greeter.

  I expect my desktop to get displayed soon after I click "Unlock" on
  the greeter.

  What happens is that there is a delay with black screen of at least 2
  seconds (often 10 minutes).

       Details:

  When I "Switch User" and then click unlock button, I get a black
  screen with no mouse cursor for 2 seconds, and then black screen with
  mouse cursor for approx 0.65 seconds for every minute my PC was in
  DPMS (after 495 minutes in DPMS the black screen is up for a very long
  321 seconds).  If I'm on greeter screen and keep moving mouse to avoid
  DPMS, then I only have the 2 second delay.

  This only happens with NVidia drivers (nouveau drivers don't have any
  delay at all). I tested on fresh installs of both Ubuntu 19.10 with
  default gdm and UbuntuStudio 19.10 with LightDM and now UbuntuStudio
  20.04 nightly build. If I prevent DPMS by moving my mouse every few
  minutes, then I only have the 2 second delay. I am not able to
  reproduce this issue on UbuntuStudio 18.04.

  Methods that cause delay:
  - Click "Switch User" on the Whisker menu. 
  - Click "Switch User" on the "Action Buttons" on panel 0. 
  - dm-tool switch-to-greeter   (displays greeter)
  - dm-tool lock                (starts DPMS, then greeter)

  Methods that DO NOT cause delay:
  - Click "Lock" on the Whisker menu. 
  - Click "Lock" on the "Action Buttons" on panel 0. 
  - xdotool key Ctrl+alt+l      (runs screensaver, only delay if click "Switch User")
  - xflock4                     (runs screensaver, only delay if click "Switch User")
  - xset dpms force off         (runs screensaver, only delay if click "Switch User")

  Another interesting symptom is that the first 2 second black screen
  does have the mouse pointer in 19.10, but not in 20.04.  Also, If I
  Lock instead of Switch User, then my desktop comes up immediately.

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: lightdm-gtk-greeter 2.0.6-0ubuntu1
  ProcVersionSignature: Ubuntu 5.4.0-14.17-lowlatency 5.4.18
  Uname: Linux 5.4.0-14-lowlatency x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.11-0ubuntu18
  Architecture: amd64
  Date: Sun Mar  1 00:56:12 2020
  InstallationDate: Installed on 2020-02-29 (0 days ago)
  InstallationMedia: Ubuntu-Studio 20.04 LTS "Focal Fossa" - Alpha amd64 (20200227)
  ProcEnviron:
   LANGUAGE=en_US
   TERM=xterm-256color
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: lightdm-gtk-greeter
  UpgradeStatus: No upgrade log present (probably fresh install)

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