How to disable screen power saving in GDM3 login screen?

Question

On the desktop login screen (GDM3) my computer will put the screens into power saving mode after 15 seconds of inactivity. I would ideally like to disable power saving in this situation, or at least lengthen the period.

I have tried disabling all power saving options that I can find in gsettings, both for my user and for root, but this has not affected the 15 second timeout.

What else can I try?

I'm running Ubuntu 19.04 with Gnome Shell 3.32.2. I have found various older questions concerned with the same issue, but they all relate to LightDM:

• How do I prevent my display from turning off when screen is locked?
• How to disable sleep/suspend at login screen?

Answer 1

This default setting (suspend at login) affects me in Pop!os 20.04. When away from home I want to login to my home PC, and it is set to boot at 6am. But that's no use when it suspends :)

This is an easy fix:

From: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=893964#22

It's 20 minutes, and is a result of the defaults in gnome-settings-daemon 3.28 changing to comply with European and American power-saving regulations.

there appears to be no way of switching the GDM suspend behaviour off

There's currently no UI for it, but if you append this to /etc/gdm3/greeter.dconf-defaults:

# Automatic suspend
# =================
[org/gnome/settings-daemon/plugins/power]
# - Time inactive in seconds before suspending with AC power
#   1200=20 minutes, 0=never
sleep-inactive-ac-timeout=0
# - What to do after sleep-inactive-ac-timeout
#   'blank', 'suspend', 'shutdown', 'hibernate', 'interactive' or 'nothing'
sleep-inactive-ac-type='nothing'
# - As above but when on battery
# sleep-inactive-battery-timeout=1200
# sleep-inactive-battery-type='suspend'

then reboot (or run "service gdm3 reload" as root), that should put the GDM session back to the pre-3.28 behaviour. The values are in seconds, with 0 meaning never; please adjust as needed.

Note: this still works in Ubuntu 21.10. Also, if you want the screens to go into suspend mode but you don't want to suspend, set a timeout, and set the type to be 'blank'

For changes to take effect, reboot or

sudo systemctl restart gdm3 

Answer 2

Create /etc/dconf/profile/gdm and add:

user-db:user
system-db:gdm
file-db:/usr/share/gdm/greeter-dconf-defaults

Create /etc/dconf/db/gdm.d/01-power and add:

[org/gnome/settings-daemon/plugins/power]
sleep-inactive-ac-timeout=0
sleep-inactive-ac-type='nothing'

Run sudo dconf update

Answer 3

xset -dpms disables DPMS, meaning you will see a black screen, not an off monitor. xset +dpms re-enables it.

xset s 300 changes the timeout to 300 seconds.

Neither of these commands persist across logout, but you can add them to ~/.xsession.

Answer 4

Run the following script as root :

#!/bin/bash

cat > /etc/lightdm/lightdm.conf.d/50-dpms.conf <<EOF
echo '[SeatDefaults]
display-setup-script=/usr/local/bin/dpms-stop'
EOF


cat > /usr/local/bin/dpms-stop <<EOF
#!/bin/sh
sudo xhost +si:localuser:lightdm 
sudo su lightdm -s /bin/bash <<HERE
/usr/bin/xset -dpms
exit
HERE
EOF

chmod +x /usr/local/bin/dpms-stop

Then reboot