[Asus Eee PC X101CH] Display brightness is always 0 and the screen is hardly readble after boot

[Nir Soffer]

After boot, display brightness is always 0 and the screen is hardly readable.
cat /sys/class/backlight/acpi_video0/brightness -> 7
cat /sys/class/backlight/psb-bl/brightness -> 0

Workadound

To fix the system brightness, open the terminal application and run these commands:

sudo -s
[enter your password]
echo 80 > /sys/class/backlight/psb-bl/brightness
exit

For permentant fix edit /etc/rc.local as root, and add this line before the line "exit 0":

echo 80 > /sys/class/backlight/psb-bl/brightness

You may use any value from 0 to 100 instead of 80.
---
ApportVersion: 2.6.1-0ubuntu10
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: nirs 2070 F.... pulseaudio
DistroRelease: Ubuntu 12.10
HibernationDevice: RESUME=UUID=4cebec9a-7504-469c-8677-d25304edfd40
InstallationDate: Installed on 2012-06-08 (267 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
MachineType: ASUSTeK COMPUTER INC. X101CH
MarkForUpload: True
Package: linux (not installed)
ProcFB: 0 psbfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.5.0-26-generic root=UUID=8a182610-1789-4b8d-b2e3-18f776104030 ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.5.0-26.40-generic 3.5.7.6
RelatedPackageVersions:
 linux-restricted-modules-3.5.0-26-generic N/A
 linux-backports-modules-3.5.0-26-generic N/A
 linux-firmware 1.95
Tags: quantal
Uname: Linux 3.5.0-26-generic i686
UpgradeStatus: Upgraded to quantal on 2013-02-22 (7 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
dmi.bios.date: 01/06/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: X101CH.0501
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: X101CH
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: x.xx
dmi.chassis.asset.tag: 0x00000000
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: x.x
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrX101CH.0501:bd01/06/2012:svnASUSTeKCOMPUTERINC.:pnX101CH:pvrx.x:rvnASUSTeKCOMPUTERINC.:rnX101CH:rvrx.xx:cvnASUSTeKCOMPUTERINC.:ct10:cvrx.x:
dmi.product.name: X101CH
dmi.product.version: x.x
dmi.sys.vendor: ASUSTeK COMPUTER INC.

[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

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[Nir Soffer (nirsof)]

Like https://bugs.launchpad.net/ubuntu/+source/linux/+bug/765438 - but I'not sure it is a duplicate.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Nir Soffer (nirsof)]

Fixed if adding this to the boot parameters:

acpi_osi=Linux acpi_backlight=vendor

But in this mode the system freeze when you try to change the brightness using the hardware keys (Fn + F5, Fn + F6).

[Nir Soffer (nirsof)]

Tested with kernel 3.9.0-rc1 (http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.9-rc1-raring/)

Partialy fixed - brightness is now 100 (maximum value) on reboot instead of 0.

Expected: brightness should be the same value set by the user.

[penalvch (penalvch)]

Nir Soffer, as per http://www.asus.com/Notebooks_Ultrabooks/Eee_PC_X101CH/#support_Download_8 an update is available for your BIOS (1203). If you update to this, does it change anything?

If not, could you please both specify what happened, and provide the output of the following terminal command:
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

Thank you for your understanding.

[Launchpad Janitor (janitor)]

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