Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: xserver-xorg-input-evdev (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1042359

Title:
  Brightness hotkeys not seen by kernel on Asus n55s, other hotkeys ok.

Status in “xserver-xorg-input-evdev” package in Ubuntu:
  Confirmed

Bug description:
  On an Asus n55sf, there is an issue with the handling of brightness
  adjust keys.

  ## Severity: consistent annoyance for the target human user

  Rationale:
  * On this laptop, the most natural way to set LCD brightness (hotkeys) 
*seems* to work at first.
  * But the user's choice is consistently overriden.
  * More precisely: it is overriden whenever, on batteries, there is a pause in 
keyboard/mouse activity (e.g. when the user reads text on-screen, or comes back 
to the laptop after a minute).

  * Caveat: the problem is *not* the laptop dimming the brightness to
  save power, this is expected behavior.  The problem is, when user
  provides events again, brightness is not reverted to value set by
  hotkeys.

  ## Context

  * X session, it can be Unity or other (e.g. xfce), scenario is the same.
  * Bug noticeable when running on batteries (due to automatic brightness 
change on idle).

  ## Expected behavior

  * pressing Fn-F5 and Fn-F6 changes the brightness
  * pressing Fn-F5 and Fn-F6 show on-screen notification
  * on battery after 30 seconds without key/mouse event, backlight is dimmed. 
Then, pressing any key or moving mouse restores brigthness at the value set 
using keys

  ## Observed behavior

  * pressing Fn-F5 and Fn-F6 changes the brightness -> OK
  * pressing Fn-F5 and Fn-F6 *does not* show on-screen notification -> minor
  * on battery after 30 seconds without key/mouse event, backlight is dimmed. 
Then, pressing any key or moving mouse restores brigthness at the last value 
set using software (gnome-control-center, xbacklight, whatever, but *not* the 
brightness set using keys) -> bad

  ## Steps to reproduce

  * set backlight to 100% (using gnome-control-center or "xbacklight =100" 
(usage scenario : on AC, need bright display)
  * unplug AC power to run on battery
  * change brightness using Fn-F5, e.g. some value halfway (usage scenario : 
now on the move, need to save power)
  * count a little more than 30 seconds without touching 
keyboard/touchpad/mouse, see brightness reduces to minimum
  * press e.g. shift, or move mouse or touchpad
  * expected : brightness jumps to halfway (set using hotkeys)
  * observed : brightness jumps to maximum (set using software)

  ## Additional information

  * Other keys work: sound volume, wifi toggle, touchpad toggle, sound 
play/pause/previous/next/stop
  * Some working keys *do* display OSD feedback (at least volume up/down/mute, 
touchpad toggle, sound play/pause/previous/next/stop)
  * Some working keys do not display OSD feedback (wifi toggle, supend, LCD 
toggle, LCD/external display toggle)

  * On a different laptop, Asus X77VN, brightness keys do show on-screen
  notification with percentage bar, and the bug is never experienced.
  Laptop is different model but same brand and software, same packages,
  same system and user settings (Unity or xfce, same behaviour).

  ## Interpretation

  * Everything seems consistent with the interpretation that although
  brightness hotkeys do work, Ubuntu is never aware of that. So when
  Ubuntu changes the brightness, it can not do better than use the value
  set using software.

  ## Workaround

  * In gnome control center, uncheck "Dim screen to save power". A quick
  test shows that Ubuntu does not change brightness, so user preference
  set by hotkey is preserved.


  
  ## Other

  $ lsb_release -rd
  Description:  Ubuntu 12.04.1 LTS
  Release:      12.04

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: xorg 1:7.6+12ubuntu1
  ProcVersionSignature: Ubuntu 3.2.0-30.48-generic 3.2.27
  Uname: Linux 3.2.0-30-generic x86_64
  .tmp.unity.support.test.0:
   
  ApportVersion: 2.0.1-0ubuntu12
  Architecture: amd64
  CompizPlugins: 
[core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom]
  CompositorRunning: compiz
  Date: Mon Aug 27 19:24:46 2012
  DistUpgraded: Fresh install
  DistroCodename: precise
  DistroVariant: ubuntu
  ExtraDebuggingInterest: Yes,
  GraphicsCard:
   Intel Corporation 2nd Generation Core Processor Family Integrated Graphics 
Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
     Subsystem: ASUSTeK Computer Inc. Device [1043:2050]
   NVIDIA Corporation GF106 [GeForce GT 555M] [10de:1247] (rev ff) (prog-if ff)
  InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120419)
  MachineType: ASUSTeK Computer Inc. N55SF
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-30-generic 
root=UUID=31c3e78d-5937-43bd-b4b2-e14e52d2898c ro quiet splash vt.handoff=7
  SourcePackage: xorg
  Symptom: display
  UpgradeStatus: No upgrade log present (probably fresh install)
  XorgConf:
   Section "Device"
        Identifier      "Default Device"
        Option  "NoLogo"        "True"
   EndSection
  dmi.bios.date: 08/29/2011
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: N55SF.207
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: N55SF
  dmi.board.vendor: ASUSTeK Computer Inc.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK Computer Inc.
  dmi.chassis.version: 1.0
  dmi.modalias: 
dmi:bvnAmericanMegatrendsInc.:bvrN55SF.207:bd08/29/2011:svnASUSTeKComputerInc.:pnN55SF:pvr1.0:rvnASUSTeKComputerInc.:rnN55SF:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
  dmi.product.name: N55SF
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK Computer Inc.
  version.compiz: compiz 1:0.9.7.8-0ubuntu1.4
  version.ia32-libs: ia32-libs N/A
  version.libdrm2: libdrm2 2.4.32-1ubuntu1
  version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.3+8.0.2-0ubuntu3.2
  version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
  version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.3+8.0.2-0ubuntu3.2
  version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu10.7
  version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.0-0ubuntu1.2
  version.xserver-xorg-video-ati: xserver-xorg-video-ati 
1:6.14.99~git20111219.aacbd629-0ubuntu2
  version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4.1
  version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 
1:0.0.16+git20111201+b5534a1-1build2

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