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Akisame
Asked: 2014-12-25 15:20:48 +0800 CST

"monitor brightness down" key resets brightness before lowering it

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My monitor brightness down key resets my brightness before lowering it, effectively leaving me at near max brightness. I do not experience any problems with the brightness up key.

I'm using a Dell XPS 15 laptop with an NVIDIA gpu. Its a fresh install of Ubuntu 14.04 with gnome 3 and it worked fine with 13.04 with unity. I added GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor" to my grub file (since this was the solution in 13.04 and I've added

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

EndSection

to /usr/share/X11/xorg.conf.d/20-intel.conf

I can change my brightness with a workaround but I would like to use the normal brightness controls.

Edit: I removed the GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor" part from my grub and changed it back to "quiet splash".

My brightness down key keeps on resetting the brightness. I've mapped another key to the same keycode (224, monitor brightness down) and it works fine! Why is the normal brightness down key not working?

When I open a virtual terminal (Ctrl+Alt+F1) and press the brightness down key I get a time stamp with the text ACPI: failed to switch the brightness (which is expected) and the brightness resets anyway (which is unexpected).

Meaning that the resetting of the brightness isn't linked to the "brightness down" command under the key but linked to the key itself. Some secondary command, bug or something else.This is confirmed by disabling the brightness controls using dconf-editor. Even after disabling these controls the brightness down button resetted the brightness.

nvidia

1 Answers

  1. After you installed in terminal with

    sudo apt-get install xrand*

    Goto dash-symbol at top of unity-bar (left side)

    a) - then type "sys" into the input-line for text -

    b) - there you can see the symbol for keyboard click on it -

    c) - then you can define the appropriate what-to-do-for-you by hitting the certain key on your desktop

    d) - you can add some code into the desription of your certain key-to-define-your-wish-to-perform-your-command

    e) - by this you can add too the command for to dim xrand the proper values suiting to your screen or to your graphics-card (due to your voltage of your electricity cable at home)

    Here is a description about the xrand-command and you only would need to pick out of this the correct display-size of your graphics-card.

    http://www.ubuntugeek.com/how-change-display-resolution-settings-using-xrandr.html

    Cheers.

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