screen brightens when idle, rather than dimming

[ChrisLees]

This may be related to the bug #498974 (https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/498974)

When the screen is turned to a high brightness, if I haven't touched the keyboard or mouse for a while the display will dim a bit. This is normal.

However, when the screen is at a low brightness, at idle the screen will actually brighten instead of dim!

It seems like the "brightness to dim to" is a hardcoded value, rather than relative to the current brightness. Hence, the hardcoded "brightness to dim to" is actually brighter than what I have my screen set to.

It seems related to that other bug, but the symptoms they report are a little different. Mine just gets a bit brighter. The other bug report describes the screen getting to full brightness before dimming somewhat again, ending off with a higher brightness than when the keyboard and mouse are not idle.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: gnome-power-manager 3.1.3-0ubuntu2
ProcVersionSignature: Ubuntu 3.0.0-9.14-generic 3.0.3
Uname: Linux 3.0.0-9-generic i686
Architecture: i386
Date: Sun Aug 28 18:44:10 2011
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GnomeSessionSuspendInhibited: No
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Alpha i386 (20110705.1)
MachineType: Acer Aspire one
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-3.0.0-9-generic root=UUID=102e52fc-bde4-407b-97a7-a4c8cb0e09bf ro rootflags=subvol=@ quiet splash vt.handoff=7
SourcePackage: gnome-power-manager
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/14/2009
dmi.bios.vendor: Acer
dmi.bios.version: V1.22
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Aspire one
dmi.board.vendor: Acer
dmi.board.version: V1.22
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.22
dmi.modalias: dmi:bvnAcer:bvrV1.22:bd10/14/2009:svnAcer:pnAspireone:pvrV1.22:rvnAcer:rnAspireone:rvrV1.22:cvnAcer:ct10:cvrV1.22:
dmi.product.name: Aspire one
dmi.product.version: V1.22
dmi.sys.vendor: Acer
gnome-power-bugreport: Error: [Errno 2] No such file or directory

[Alex Stevens (alex-stevens)]

Exact same problem on an Asus Eee PC 1000HA.
I have used the function keys to dim the screen to its minimum, and it seems the default "Dim on Idle" exhibits the exact characteristics that Chris mentioned. Instead of dimming further (or to the same minimum level), it will actually brighten to about a 25-30% setting.

It would be expected that the "Dim on Idle" dim in relation to the current brightness level, rather than to a set level.
E.g.
min_level >= (0.25 * current_level) ? dim _level = min_level : dim_level = 0.25 * current_level;
Rather than...
dim_level = 0.25 * max_level;