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Nov
13
2011

Enabling brightness controls on an HP Envy 17 under Fedora 16

I’ve recently set up Fedora 16 on my laptop, and all has been smooth, save for the brightness switches. The on-screen display would show up when I used the fn-F2/fn-F3 key combinations, but the brightness just wouldn’t change. Additionally, the brightness was stuck at the lowest level.

Turns out there’s a pretty easy fix in the form of a couple of module parameters:

In /etc/defaults/grub, add the following kernel parameters:

video.brightness_switch_enabled=1 video.use_bios_initial_backlight=0

(You may also want to add radeon.modeset=1 and acpi_osi=Linux for this particular machine, but they aren’t related to the brightness fix.)

Then update your grub2 config:

 grub2-mkconfig > /boot/grub2/grub.cfg

Reboot, and your brightness controls should work as expected. The brightness slider in GNOME still doesn’t work, but I’m content with hardware brightness controls over no brightness controls.

  • Nick

    Cheers, Fixed up my HP DM3. Gnome brightness slider works too :D

  • Rodrigo

    sorry, i’m really new in fedora, well in linux. Just runing away from windows 7 starter.

    and with fedora 16 is the first that a linux distribution works perfect on mi notebook.

    My only one problem is the brightness of the screen. it’s always on max. and my problem is that i’m starting to learn how to use the terminal.

    When i’m in /etc/default i could enter to grub with “gedit grub” but i couldt sae the changes. But as root, i couldn’t enter with “gedit grub” 

    (gedit:9822): EggSMClient-WARNING **: Failed to connect to the session manager: None of the authentication protocols specified are supported** (gedit:9822): WARNING **: Could not connect to session busCould someone explein me how to add this kernel parameter in the grub, pplease!!!!i’m new in linux, and i speak spanish, so sorry for my redaction!!! and aparently this is the only forum where the problem es fixed, and in a very simple way!!THANKS!!!

  • Don Mccormick

    This fixed my HP Pavilion dv7.

    Before I had to add number to /sys/class/backlight/acpi_video0/brightness as root which was an annoyance for my wife.

    BTW. You have a minor typo, the file is /etc/default/grub but the overall fix is sound.

    You have my thanks

  • Don Mccormick

     In the /etc/default/grub file you will most likely see a line like:

    GRUB_CMDLINE_LINUX=”quiet rhgb”

    Modify so it looks like the following:

    # GRUB_CMDLINE_LINUX=”quiet rhgb”
    GRUB_CMDLINE_LINUX=”quiet rhgb video.brightness_switch_enabled=1 video.use_bios_initial_backlight=0″

    Note I like to keep the original line just in case so I comment the original setting out (see the “#”). It is also a good idea to save your original grub config file although it is easy to check with grub2-mkconfig if the changes are going to work. That is create a separate file in say /tmp and run a diff on the /boot/grub2/grub.cfg and the file you just created.

    If in the unfortunate situation something goes wrong you can always boot to single user mode or rescue mode (this can get a bit messy and is really out of scope in this reply) and run “grub2-mkconfig” on the original /etc/default/grub file to recreate the original /boot/grub2/grub.cfg file.

    You can even edit the “vmunix” boot options (ie. when you see the initial boot menu type “e” and select the second line with your cursor keys then again using the cursor keys for moving your cursor and backspace key for deletion you can add by typing appropriate options). This method is excellent to test out new parameters since you just need to reboot to get back to your original settings.  It is usually a good idea to have a pen and paper handy when doing this so you can add to the /etc/default/grub file when satisfied.