Max screen brightness differs depending on power status at boot

[Martin Thompson]

Binary package hint: xorg

If I boot with the mains connected my screen brightness can be adjusted from very bright to dim, but perfectly usable.

If I boot just on battery power, it varies from something similar to "dim but perfectly usable" as above to blank (backlight off)

I think I've seen that the BIOS sets the screen brightness at startup differently when booting with and without mains, so might that be setting what Ubuntu thinks is maximum brightness. For comparison, Win7 doesn't do this, the very bright setting is available both ways.

On resumption from sleep or hibernate, the behaviour is as it was before (irrespective of whether resume is done with or without mains)

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-25.45-generic 2.6.32.21+drm33.7
Uname: Linux 2.6.32-25-generic i686
NonfreeKernelModules: wl
Architecture: i386
Date: Wed Nov 24 20:51:58 2010
DkmsStatus:
 bcmwl, 5.60.48.36+bdcom, 2.6.32-21-generic, i686: installed
 bcmwl, 5.60.48.36+bdcom, 2.6.32-24-generic, i686: installed
 bcmwl, 5.60.48.36+bdcom, 2.6.32-23-generic, i686: installed
 bcmwl, 5.60.48.36+bdcom, 2.6.32-25-generic, i686: installed
 bcmwl, 5.60.48.36+bdcom, 2.6.32-22-generic, i686: installed
InstallationMedia: Ubuntu-Netbook 10.04 "Lucid Lynx" - Beta i386 (20100406.1)
MachineType: Hewlett-Packard HP Mini 5102
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-25-generic root=UUID=5948c4f9-eb12-4541-967c-d9e2f98e2b8d ro splash vga=771 quiet splash
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.utf8
 SHELL=/bin/bash
SourcePackage: xorg
Symptom: display
dmi.bios.date: 03/11/2010
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68PGU Ver. F.05
dmi.board.name: 3653
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 43.1D
dmi.chassis.asset.tag: CNU01328DM
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68PGUVer.F.05:bd03/11/2010:svnHewlett-Packard:pnHPMini5102:pvr:rvnHewlett-Packard:rn3653:rvrKBCVersion43.1D:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP Mini 5102
dmi.sys.vendor: Hewlett-Packard
glxinfo: Error: [Errno 2] No such file or directory
system:
 distro: Ubuntu
 codename: lucid
 architecture: i686
 kernel: 2.6.32-25-generic

[fdsoqweo4 (nfiewiqp4n321fdsaniro34214)]

Doublepost. Marked as duplicate of the original (bug 681133)