Ubuntu – Can’t adjust brightness on the MSI VR420 laptop

11.10acpibrightnesslaptop

Using every method possible I'm unable to change my laptop brightness.. It's stuck on super max brightness.. Using the slider in the "screens" window int he control panel doesnt do anything, and using the fn keys doesn't do anything…

Some info about my system:

  • laptop is a MSI VR420

  • Running ubuntu 11.10

  • video card is an integrated intel card

  • Used to work when I ran ubuntu 10.10 and earlier versions (not sure if it worked out of the box or if I inadvertly fixed it in previous versions while installing lots of other packages)

  • Brightness slider on the "screen" window doesn't do anything, "dim when on battery -power" doesnt do anything

  • When I use the Fn+F4/F5 keys to adjust brightness there is a popup showing that its receving the input, but I can only go from between 0 brightness and max brightness.. (that is what the output is showing, the brightness does not change though)

  • when attempting to change the brightness with Fn+F4/F5 my dmesg log reports "ACPI: Failed to switch the brightness"

Here are some outputs from some terminal commands, not sure if any of this is useful or not..

lspci – http://pastebin.com/EimZSGs3

ls /sys/class/backlight/*/brightness will output:

/sys/class/backlight/intel_backlight/brightness

cat /sys/class/backlight/intel_backlight/brightness => 0 (when I use the Fn+F4/F5) this will change betwene 0 and, but the actual brightness doesn't change)

cat /sys/class/backlight/intel_backlight/max_brightness => 1

lsmod | grep ^i915 => i915 505108 3

Here is the list of things I've tried through searching google…..

  • Edit /etc/default/grub ↦ GRUB_CMDLINE_LINUX_DEFAULT: acpi_osi=Linux, acpi_backlight=vendor, nomodeset. (as well as several different combinations of these settings being on or off)

  • Edit /etc/X11/xorg.conf (file doesn't exist on my system)

  • Edit /proc/acpi/video/VGA/LCD/brightness (file doesn't exist)

  • sudo setpci -s 00:02.0 F4.B=XX (does nothing)

  • xbacklight -set XX (does nothing)

I've tried about everything with no luck… The only thing I haven't tried is adding the ppa that someone suggested here: Unable to change brightness in a Lenovo laptop …. However according to the notes on the ppa.. all of the changes that are in the ppa are now actually apart of 11.10 and the ppa is only for people with 11.04..

Does anyone have any ideas for me?

edit:by setting acpi=off in my /etc/default/grub file I was about to get my Fn+F4/F5 keys to work, also "dim when display to save power" now makes my laptop dim when on battery power.. the dimness slider however still doesn't do anything.. also xbacklight doesn't do anything stil or any of the other methods…

The thing i don't get is why setting acpi=off makes my Fn+F4/F5 keys work? Isn't acpi supposed to be enables the backlight to be dimmed? does anyone know what ubuntu is deciding to do behind the scenes when acpi=off? Does anyone know what/if any features I might be losing with it off?

Best Answer

In /etc/default/grub change:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=off"

run sudo update-grub in the terminal.

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