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Thread: Cannot change backlight brightness Ubuntu 14.04

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  1. #1
    Join Date
    Dec 2007

    Cannot change backlight brightness Ubuntu 14.04

    This morning I found that I cannot change the brightness of my Dell XPs 13 laptop's display anymore. I tried the following to change the brightness

    - Use keyboard brightness keys
    - Run the commands shown below
    - Boot with kernel option acpi_backlight=vendor. This resulted in a dell_something folder being present in the /sys/class/backlight folder. Changing the brightness file in that folder does not help.
    - Add 'intel_backlight' to xorg.conf
    - Set "load legacy option ROM" BIOS option to enabled and "secure boot" to disabled
    - Boot with kernel option i915.disable-pch_pwm=0
    - Boot from a fresh Ubuntu 12.04 USB stick installation. I can still not control the brightness. Maybe this a hardware problem?

    Any ideas why this broke suddendly? I've upgraded from 12.04 to 14.04 in April and till yesterday the brightness keys were working fine.

    echo 100 > /sys/class/backlight/intel_backlight/brightness
    echo 100 > /sys/class/backlight/acpi_video0/brightness
    Last edited by cyrus_the_virus; June 5th, 2014 at 01:08 PM.

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