Comment 0 for bug 588983

As the subject says: the backlight level on my Panasonic Let's Note CF-S9 stays at full brightness and does not physically change even though the kernel seems to believe it's changing it.

* The backlight buttons work (I get the light level slider thing).

Looking in /sys/class/backlight/panasonic:

> ls
actual_brightness bl_power brightness max_brightness power subsystem uevent

max_brightness = "21", actual brightness = "21", "brightness = "21"

If I pull down the brightness to half using the brightness controls:

max_brightness = "21", actual brightness = "10", "brightness = "10"

** But the light level doesn't actually change **

Same thing if I change it directly:

> sudo sh -c 'echo "5" >brightness'

max_brightness = "21", actual brightness = "5", "brightness = "5"

** again, no physical change in light level **

This affects the CF-S9 machine, and the CF-N9 (same machine with or without a DVD unit). It may affect the CF-Y9 and CF-R9 as well, though their hardware may be somewhat different (different cpu clock).

The main problem really is that at full brightness it is really bright, almost painful at night. Also, it really kills battery life.

Anything I can do to help debug this, let me know!

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: linux-image-2.6.32-22-generic 2.6.32-22.33 [modified: lib/modules/2.6.32-22-generic/kernel/drivers/input/tablet/wacom.ko]
Regression: No
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.32-22.33-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-22-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: HDA Generic [HDA Generic]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: janne 1412 F.... pulseaudio
CRDA: Error: [Errno 2] Filen eller katalogen finns inte
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf4a20000 irq 22'
   Mixer name : 'Intel G45 DEVIBX'
   Components : 'HDA:14f15068,10f70000,00100302 HDA:80862804,80860101,00100000'
   Controls : 9
   Simple ctrls : 4
Date: Thu Jun 3 09:38:58 2010
HibernationDevice: RESUME=UUID=6fd7f6ad-3b8d-4fc4-a6cd-206104a94db9
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
MachineType: Panasonic Corporation CF-S9JYEBDR
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-22-generic root=UUID=a1f2d382-4e79-41b4-ab46-29ae811e5102 ro quiet splash
ProcEnviron:
 LANGUAGE=sv:en
 PATH=(custom, user)
 LANG=sv_SE.utf8
 SHELL=/bin/bash
RelatedPackageVersions: linux-firmware 1.34
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: yes
SourcePackage: linux
dmi.bios.date: 03/11/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V1.00L19
dmi.board.asset.tag: No Asset Tag
dmi.board.name: CFS9-1
dmi.board.vendor: Panasonic Corporation
dmi.board.version: 1
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Panasonic Corporation
dmi.chassis.version: 001
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV1.00L19:bd03/11/2010:svnPanasonicCorporation:pnCF-S9JYEBDR:pvr001:rvnPanasonicCorporation:rnCFS9-1:rvr1:cvnPanasonicCorporation:ct10:cvr001:
dmi.product.name: CF-S9JYEBDR
dmi.product.version: 001
dmi.sys.vendor: Panasonic Corporation