GNOME Bugzilla – Bug 688179
Screen does not dim when AC is unplugged
Last modified: 2013-01-25 20:06:22 UTC
As reported in https://bugs.launchpad.net/ubuntu-nexus7/+bug/884041, when the laptop power cable is unplugged the screen no longer reduces brightness. The "dim when idle" feature does not seem to be affected. I have done a rather unscientific survey of my co-workers' laptops, all of which are running Ubuntu (as you might have guessed) 12.04 or 12.10 and they all show this regression, as does Ubuntu 12.10 running on the Nexus 7 tablet. As this is an important power-saving behavior I am curious whether this functionality was removed intentionally or if this is simply a bug.
(In reply to comment #0) > As reported in https://bugs.launchpad.net/ubuntu-nexus7/+bug/884041, when the > laptop power cable is unplugged the screen no longer reduces brightness. The > "dim when idle" feature does not seem to be affected. > > I have done a rather unscientific survey of my co-workers' laptops, all of I'd rather we had the output of: gsettings list-recursively org.gnome.settings-daemon.plugins.power than a survey of laptops that I can only guess the configuration of.
Here you go: ssweeny@talyn:~$ gsettings list-recursively org.gnome.settings-daemon.plugins.power org.gnome.settings-daemon.plugins.power active true org.gnome.settings-daemon.plugins.power button-hibernate 'hibernate' org.gnome.settings-daemon.plugins.power button-power 'interactive' org.gnome.settings-daemon.plugins.power button-sleep 'suspend' org.gnome.settings-daemon.plugins.power button-suspend 'suspend' org.gnome.settings-daemon.plugins.power critical-battery-action 'shutdown' org.gnome.settings-daemon.plugins.power idle-brightness 30 org.gnome.settings-daemon.plugins.power idle-dim-ac false org.gnome.settings-daemon.plugins.power idle-dim-battery true org.gnome.settings-daemon.plugins.power idle-dim-time 30 org.gnome.settings-daemon.plugins.power lid-close-ac-action 'suspend' org.gnome.settings-daemon.plugins.power lid-close-battery-action 'suspend' org.gnome.settings-daemon.plugins.power notify-perhaps-recall true org.gnome.settings-daemon.plugins.power percentage-action 2 org.gnome.settings-daemon.plugins.power percentage-critical 3 org.gnome.settings-daemon.plugins.power percentage-low 10 org.gnome.settings-daemon.plugins.power priority 1 org.gnome.settings-daemon.plugins.power sleep-display-ac 1800 org.gnome.settings-daemon.plugins.power sleep-display-battery 1800 org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 0 org.gnome.settings-daemon.plugins.power sleep-inactive-ac-type 'suspend' org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout 1800 org.gnome.settings-daemon.plugins.power sleep-inactive-battery-type 'suspend' org.gnome.settings-daemon.plugins.power time-action 120 org.gnome.settings-daemon.plugins.power time-critical 300 org.gnome.settings-daemon.plugins.power time-low 1200 org.gnome.settings-daemon.plugins.power use-time-for-policy true
Here it is from my laptop: org.gnome.settings-daemon.plugins.power active true org.gnome.settings-daemon.plugins.power button-hibernate 'hibernate' org.gnome.settings-daemon.plugins.power button-power 'interactive' org.gnome.settings-daemon.plugins.power button-sleep 'suspend' org.gnome.settings-daemon.plugins.power button-suspend 'suspend' org.gnome.settings-daemon.plugins.power critical-battery-action 'shutdown' org.gnome.settings-daemon.plugins.power idle-brightness 30 org.gnome.settings-daemon.plugins.power idle-dim-ac false org.gnome.settings-daemon.plugins.power idle-dim-battery true org.gnome.settings-daemon.plugins.power idle-dim-time 30 org.gnome.settings-daemon.plugins.power lid-close-ac-action 'nothing' org.gnome.settings-daemon.plugins.power lid-close-battery-action 'nothing' org.gnome.settings-daemon.plugins.power notify-perhaps-recall true org.gnome.settings-daemon.plugins.power percentage-action 2 org.gnome.settings-daemon.plugins.power percentage-critical 3 org.gnome.settings-daemon.plugins.power percentage-low 10 org.gnome.settings-daemon.plugins.power priority 1 org.gnome.settings-daemon.plugins.power sleep-display-ac 600 org.gnome.settings-daemon.plugins.power sleep-display-battery 600 org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout 0 org.gnome.settings-daemon.plugins.power sleep-inactive-ac-type 'suspend' org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout 0 org.gnome.settings-daemon.plugins.power sleep-inactive-battery-type 'suspend' org.gnome.settings-daemon.plugins.power time-action 120 org.gnome.settings-daemon.plugins.power time-critical 300 org.gnome.settings-daemon.plugins.power time-low 1200 org.gnome.settings-daemon.plugins.power use-time-for-policy true
I think it doesn't work because it was never implemented in GNOME 3.2 or later, when it was moved to gnome-settings-daemon. We only have an idle dim, which is usually sufficient, and leaves the user completely in control of the brightness (it's quite annoying when unplugging your laptop to have the backlight dim while you were looking at something). Let's see what the designers think of it.
I'll take a punt and say that we do not want to do that [1]. Right now, we don't have separate dim delays for AC and battery. If/when we do, we would need to make sure that, we would need to make sure that idles that are already past are taken into account (for example, you've been idle for 10 minutes, your current dim idle delay is 15 minutes on AC, but you unplug the device, and your dim idle delay is 5 minutes, it should dim). In bug 662972, we'll handle another case which is that plugging the machine should raise the brightness, temporarily, to the non-dimmed level. [1]: And in my experience, tablets don't do that.