GNOME Bugzilla – Bug 550524
[DPMS] GPM doesn't correctly sleep my display when DPMS is not supported by it
Last modified: 2009-05-27 21:53:07 UTC
Please describe the problem: Hello, I have an iBook and it doesn't support the DPMS specification. So, when gnome-power-manager puts my display in sleep state after N minutes (/apps/gnome-power-manager/timeout/sleep_display(ac|battery) parameters in gconf), the display is black but the backlight is always on. Steps to reproduce: 1. In the /var/log/Xorg.0.log file, you must have this line : No DPMS capabilities specified; RGB/Color Display 2. Configure the parameters /apps/gnome-power-manager/timeout/sleep_display(ac|battery) 3. and wait... Actual results: Expected results: Does this happen every time? yes Other information: There is a daemon to switch off the backlight after few minutes : pbbuttonsd (http://pbbuttons.berlios.de/). In the source code, you can see how to put the display in sleep mode. It put the level brightness to 0.
DPMS needs to be fixed.
I'm agree with you. The problem is not in gnome-power-manger. I've already created an issue on the radeon driver : https://bugs.freedesktop.org/show_bug.cgi?id=19168
I took some time to think about this problem. I saw the code in the radeon driver, in the pbuttons daemon and in GPM. First, the radeon driver do good job to switch off the video card with DPMS. Second, on Ibook, to switch off the screen, you must use Power Management Unit (PMU). There is a module on Linux system. You can control this device with /dev/pmu. The pbuttons daemon use this method to switch off the screen. The problem is to know where should be managed PMU ? in the radeon driver or in GPM ? Do you think radeon driver must control PMU when you change DPMS or GPM must control PMU himself ? For me, I think GPM should manage PMU. Tell me your opinion and if you are agree, I will create a patch.