can't adjust the brightness of my laptop display

[David Brazdil]

Binary package hint: acpi-support

This is probably an acpi-support bug, but I'm not definitely sure.
The hotkeys on my Asus UL20A worked perfectly on Karmic, however in Lucid the brightness setting keys do not anymore. The notification bubble appears but nothing happens. What's more, when I hit the key several times, it doesn't react immediately, but the notifications reappear one after another in approximately 30 seconds intervals. During this time, none of the other hotkeys work (standard keys do). Well, hotkeys do as well, but the action is processed after all of the brightness notifications.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: acpi-support 0.136
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
Architecture: amd64
Date: Mon Apr 26 08:36:04 2010
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta amd64 (20100318)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: acpi-support
---
Architecture: amd64
DistroRelease: Ubuntu 10.04
GnomeSessionIdleInhibited: Yes
GnomeSessionInhibitors: 1: AppId = Totem, Flags = 8, Reason = Playing a movie
GnomeSessionSuspendInhibited: No
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
MachineType: ASUSTeK Computer Inc. UL20A
Package: gnome-power-manager 2.30.0-0ubuntu1
PackageArchitecture: amd64
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-21-generic root=UUID=93b1d2ce-3c00-4a44-ae65-3546fb81f732 ro quiet splash
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Tags: lucid
Uname: Linux 2.6.32-21-generic x86_64
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
dmi.bios.date: 09/14/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 205
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: UL20A
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr205:bd09/14/2009:svnASUSTeKComputerInc.:pnUL20A:pvr1.0:rvnASUSTeKComputerInc.:rnUL20A:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: UL20A
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.

[Steve Langasek (vorlon)]

Thank you for taking the time to report this bug and help to improve Ubuntu.

acpi-support is not involved in changing display brightness in response to these keypresses. Reassigning to gnome-power-manager, which is closer to where this is done.

[3ntix (francesco-3ntini)]

I've the same problem. In karmik all work, but in lucid the brightness work in gnome-power-setting but the Fn hotkeys doesn't work at all.

[David Brazdil (mastiflinta)]

In response to 3ntix, I would like to add that my problem is that the brightness control doesn't work at all. No matter what I do, the brightness is always set to 100%, even when changing it in the gnome-power-manager or Brightness applet. And the hotkeys react in a weird way, as I've already written in the first post.

[Nitesh Mistry (mistrynitesh)]

Thank you for taking time out to report the problem. Just to clarify a bit, your problem is that when you press the button for reducing the brightness, the notification bubble appears and shows the brightness as reduced, but actually there is no change in brightness. Someone has reported a similar problem at bug #570734. Would you like to check the other bug and confirm this. Also, it will be very helpful to solve the problem if you run 'apport-collect 570042' from the terminal. You might also want to take a look at the debugging instructions located at https://wiki.ubuntu.com/DebuggingGNOMEPowerManager and submit any other logs related to your problem. Thanks in advance.

[David Brazdil (mastiflinta)]

Bug #570734 sounds similar, however it is not exactly what happens to me. What you said is correct, pressing the hotkeys doesn't change brightness, nor does any other application in the system (Brightness applet, gnome-power-manager). But what's weirdest is that when pressing the hotkey several times, the notification bubble should change immediatelly, but it changes step by step with 30 sec pauses between them. And other hotkeys "wait in the queue" too, normal keys don't. Just to make it crystal clear here's an example: I type "brightness up" three times, "volume up" two times. What happens is: "brightness up", 30 sec pause, "brightness up", 30 sec pause, "brightness up", "volume up", "volume up". By the way, it's EXACTLY 30 sec. Weird, isn't it?
Yesterday, I reinstalled the system, to be sure that it isn't just some kind of my own mistake, but it isn't - the bug is still there.

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

apport information

[David Brazdil (mastiflinta)]

Uploaded the requested information. Hope it helps...

Just one more thing a probably should have mentioned - the problem with pauses between hotkeys typings appears only with those for brightness adjustment, other hotkeys are fine.

[otkaz (lsellens)]

Same problem here using on a HP elitebook 8530p. FN keys and desktop display applet will not adjust the display. when I first boot my display is pretty bright with either it plugged into ac or not until i either plug or unplug for the first time then the display dims some, but will not get bright again plugged or unplugged, also /proc/acpi/video/DGFX/LCD/brightness shows it set to 100% at all times it never changes. I'm using the ati driver tried running aticonfig --acpi-services off, but it made no difference. It worked fine in karmic and ibex...

[David Brazdil (davidbrazdil)]

Hey everyone,
I've just found a workaround for this problem somewhere deep in the waters of Internet. For me and my Asus UL20A it worked like a charm, so hopefully, it may be useful to some of the others here.

1) open /etc/default/grub
2) add "acpi_backlight=vendor acpi_osi=linux" to GRUB_CMDLINE_LINUX
3) run sudo update-grub
4) restart your computer