DPMS Turns Itself On

[Dutchman]

It could be a bug in the kernel modules 'acpi' and/or 'apm' or the daemons that work with them, acpid and/or apmd. You can find out by temporarily disabling them.

Reboot the machine, and when the grub menu appears, press "e" to edit the boot configuration. On Ubuntu-based distros you may have to hold down the SHIFT key after the computer's POST messages to get to the grub menu, keep SHIFT held down until you see the menu. Don't worry, what you change here will only apply until the next reboot. Once in the edit screen, find the line that starts with "linux" and has things like "ro splash quiet" and other stuff in it. Move the cursor over to somewhere after "ro" and type in:

acpi=off

or if on a laptop:

noapm

Then press F10 to continue booting. If your screen blanking stops, you've found what's triggering it. Note though that these modules control other power features too, so you may need to keep an eye on your system behavior to see if anything else goes a bit wonky before adding it permanently to /boot/grub/grub.cfg. It also wouldn't hurt to open a terminal and run "dmesg | less" to look at the system log to see if anything is having problems because of these modules being turned off.

You can find info on these modules in your '/usr/share/doc/' folder that may be of some help.

[Mr_Bumpy]

I can confirm that running Muon causes DPMS to be re-enabled. This seems to happen during the process where Muon tells Solid to supress sleep/monitor blanking while it does its updates. The bug is probably in Solid and appears to be fixed in current KDE GIT (although I can't confirm this). Here are the related KDE bug reports: #306490, #295164. At the bottom of the second link there is a review request that should fix the problem.

[Guest]

Hi,

I installed kubuntu 12.04.1, earlier today and run into this bug and stumbled across this thread looking for a solution. I believe I have figured out a workaround for now (for those who don't want to compile KDE from source and don't mind disabling power management completely), so I thought I'd post it here, since I haven't seen it anywhere else.

THE BUG: performing some actions such as (un)installing a package in muon cause dpms to be enabled overriding kde power management settings (others have reported using dragon or vlc or copying a file with dolphin can trigger the problem, I believe). xset -q reveals dpms has been switched on with apparently random setting for Standby, Suspend and Off. xset -dpms will temporarily fix this, until the bug is activated again (e.g. through muon).

THE WORKAROUND:

1) Go to System settings > Startup and Shutdown > Service Manager and disable Power Managment

2) Create the following script (similar to one proposed earlier in the thread):

#!/bin/bash

xset dpms 0 0 0
xset -dpms

name it "nodpms" (say) and chmod +x it and move it to ~/.kde/Autostart. Then logout and in again, and the fix should be in place. Installing a package in muon no longer enables dpms. Note: You need this script otherwise dpms defaults to on at login, but I guess disabling dpms in xorg.conf instead of the above script will probably have the same effect, but I've not tried it.

Hope this helps someone else.

[Snowhog]

Nice post. I've copied to our How To's board.

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