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    Brightness control doesn't work on HP dv7t laptop

    I am completely unable to control the brightness on my new HP dv7t laptop; neither its brightness control buttons nor any software solution I've tried has worked. Here's my card's specs:

    Code:
    Intel(R) HD Graphics 3000 [HDMI, VGA]
    Note that sometimes the onscreen display comes on when I attempt to adjust the brightness, whether via the buttons or software...and sometimes it doesn't. I have no idea why. But one thing that's consistent is that I cannot adjust the brightness! Any ideas?
    Xenix/UNIX user since 1985 | Linux user since 1991 | Was registered Linux user #163544


    #2
    Re: Brightness control doesn't work on HP dv7t laptop

    You can try adding noapic to the line GRUB_CMDLINE_LINUX="" in /etc/default/grub so that it reads:
    GRUB_CMDLINE_LINUX="noapic"
    Save and close the file and then in a console type:
    Code:
    sudo update-grub
    Reboot and see if the brightness controls (fn+f2 and fn+f3 here on my Pavilion g7) work. Be warned, that if it works, you may loose keyboard control of the wireless function key.
    Windows no longer obstructs my view.
    Using Kubuntu Linux since March 23, 2007.
    "It is a capital mistake to theorize before one has data." - Sherlock Holmes

    Comment


      #3
      Re: Brightness control doesn't work on HP dv7t laptop

      Originally posted by Snowhog
      You can try adding noapic to the line GRUB_CMDLINE_LINUX="" in /etc/default/grub so that it reads:
      GRUB_CMDLINE_LINUX="noapic"
      Save and close the file and then in a console type:
      Code:
      sudo update-grub
      Reboot and see if the brightness controls (fn+f2 and fn+f3 here on my Pavilion g7) work. Be warned, that if it works, you may loose keyboard control of the wireless function key.
      Okay, I did the above--and I did not lose anything! I gained control of brightness, but NOT via the keys on the laptop. I can now go to System Settings | Display and Monitor | Gamma and adjust the brightness up/down from there. It's a hassle, but at least it works! Thanks for the point in the right direction. I hadn't even thought about noapic in years...I remember one of my earlier laptops had some kind of issue that I solved by adding noapic to it during installation, but that was a while back!
      Xenix/UNIX user since 1985 | Linux user since 1991 | Was registered Linux user #163544

      Comment


        #4
        Re: Brightness control doesn't work on HP dv7t laptop

        Well, good. I had similar issues with my HP g7 'initially', and tried several kernel= options. You might want to try this (as apposed to, or in addition to):

        acpi.power_nocheck=1
        acpi=noirq
        Windows no longer obstructs my view.
        Using Kubuntu Linux since March 23, 2007.
        "It is a capital mistake to theorize before one has data." - Sherlock Holmes

        Comment


          #5
          Re: Brightness control doesn't work on HP dv7t laptop

          Some nVidia cards require adding a line to /etc/X11/xorg.conf in the "DEVICE" section:

          Code:
          Option "RegistryDwords" "EnableBrightnessControl=1"
          I wonder whether that might work on Intel graphics chips too?

          Also, I just noticed a page about debugging backlight problems in the Kubuntu wiki.

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