Backlight behaves erratically when changed from keyboard.

[oliver]

Binary package hint: gnome-power-manager

I've set up gnome-power-manager to "Dim when Idle" and "reduce when on battery" to manage my display.

Sometimes, while i'm in dark conditions(with or without AC) or want to maximize battery life, I use the keyboard shortcuts (fn-home + fn-end on a T42) to dim the display to it's minimum. However, mostly while reading stuff and thus not interacting and letting the 'dim timer' kick in, in stead of trying to dim the display, it turns quite bright for a second and then dims it again, but to a higher setting then what it was at. Not only does this blind me, it is also highly annoying.
This also happens during boot, when I have the setting dimmed and just before login the power-manager backend kicks in to do it's dim-undim magic.

The first thing gnome-power-manager should do (or it's backend) is try to determine what the current backlight setting is. I know this is possible on a IBM T42 as this issue wasn't here 2 release ago.

ProblemType: Bug
Architecture: i386
Date: Mon Dec 21 09:11:01 2009
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/bin/yelp
Package: yelp 2.28.0-0ubuntu2
ProcEnviron:
 LANG=C
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-16.53-generic
SourcePackage: yelp
Uname: Linux 2.6.31-16-generic i686
---
Architecture: i386
DistroRelease: Ubuntu 10.10
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GnomeSessionSuspendInhibited: No
Lsusb:
 Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: IBM 2373a23
Package: gnome-power-manager 2.32.0-0ubuntu1
PackageArchitecture: i386
PccardctlIdent:
 Socket 0:
   no product info available
 Socket 1:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
 Socket 1:
   3.3V 32-bit PC Card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.35-24-generic root=UUID=80ae20de-3ab0-479b-91da-fd2366386885 ro quiet splash radeon.agpmode=4
ProcEnviron:
 LANGUAGE=nl_NL:en_US:en
 LANG=nl_NL.utf8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.35-24.42-generic 2.6.35.8
Tags: maverick ubuntu-une
Uname: Linux 2.6.35-24-generic i686
UserGroups: adm admin cdrom dialout lpadmin netdev plugdev sambashare
dmi.bios.date: 06/18/2007
dmi.bios.vendor: IBM
dmi.bios.version: 1RETDRWW (3.23 )
dmi.board.name: 2373a23
dmi.board.vendor: IBM
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: IBM
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnIBM:bvr1RETDRWW(3.23):bd06/18/2007:svnIBM:pn2373a23:pvrThinkPadT42:rvnIBM:rn2373a23:rvrNotAvailable:cvnIBM:ct10:cvrNotAvailable:
dmi.product.name: 2373a23
dmi.product.version: ThinkPad T42
dmi.sys.vendor: IBM

[Felix Zweig (f.zweig)]

I have the same problem on a DELL XPS M1330 using the proprietary Nvidia drivers. Often, the brightness is also kept after a reboot, even after changing from AC to battery or vice-versa.

[WeatherGod (ben-v-root)]

I can confirm this odd behavior on my EeePC (even on AC power) using 9.04 UNR. If I modify my current brightness using the hotkeys, the screen will later change its brightness to something else. Also, I don't think it is related to going into or out of idle, and I can't seem to notice a particular trigger for it.

The only work-around I have figured out is to change the brightness level from within gnome-power-manager and not touch the hotkeys.

[Wyatt Best (wyattbest)]

I am also experiencing this on my EeePC 1005HA running Ubuntu Netbook Remix (UNR) 9.10.

I use XP more than Linux on this netbook primary because of this maddening behavior. Also, why can't I make the screen dimmer? The lowest brightness setting is still pretty bright, and I know the hardware can go lower because the screen does a fancy dimming animation with many steps when it goes to sleep.

[WeatherGod (ben-v-root)]

Wyatt, have you tried to modify the screen brightness from the Power Management? I find I have the most issues when I try to change the screen brightness using the hotkeys. But I have not had issues if I do it from the Power Management.

[Wyatt Best (wyattbest)]

I cannot find a way to change the screen brightness when running on battery. There is a slider for brightness when on AC power, but it does not affect anything when running on battery.

[WeatherGod (ben-v-root)]

Wyatt, you are correct. I might have been confused with a different version. The power manager in Karmic does not allow for one to modify the "On Battery" screen brightness (except for an option to dim the screen a bit from the "On AC" level).

[oliver (oliver-schinagl)]

10.10 still has the same issue :S

[Victor Vargas (kamus)]

Oliver, Could you please open a terminal and execute: apport-collect 498974 ? It will attach the necessary information to this report. Also you can submit more information for it by looking to https://wiki.ubuntu.com/DebuggingGNOMEPowerManager , Thanks in advance.

[Launchpad Janitor (janitor)]

[Expired for gnome-power-manager (Ubuntu) because there has been no activity for 60 days.]

[oliver (oliver-schinagl)]

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[oliver (oliver-schinagl)]

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[Carlos Moffat (carlos-eldiabloenlosdetalles)]

I hope this will be considered as a Paper Cut. It's really quite annoying, and a new user wouldn't quite know how to fix it.

[ChrisLees (christopher-lees)]

It's too big a problem to be a paper cut. A paper cut should be a minor issue that requires only a small amount of effort to repair. This bug would require delving into the code.