Brightness control stoped woring right after bios update


I have this strange problem that seems common, but couldnt find any other posts with help for me (or I couldnt figure out)

I have updated my bios and after that the FN+F2 (less brightness) and FN+F3 (more brightness) stoped working as they used to.

Now the just bring the brightness low or high, there is no middle settings. I open my Windows7 Home partition and there is no problem, the brightness still works (sadly :’()

So, I think that maybe there is a setting saved somewhere (with my old bios paramenters) that I need to delete or “redetect”… (just guessing)

Could you help me?


Roll back the update
or did you update for any specific reason?

I prefer not to rollback the bios update because the last update solve some problems with tempratures.

I thought that maybe with my last bios for i.e. my min and max brightnes would be suppose 0-100 and now its 0-10 or something like that messup…

Do you think there is any other solution? could it be a setting that needs updating?


Try a new user account, but it may be the same. But it’s a good way to test user settings (That’s all we are doing it for, so you can delete it later)
It’s unlikely, but lets see.

I created the user as you told and test it, but unfortunately when I start the session its worst :frowning: FN+F2 and FN+F3 does nothing at all.

So, its should be a setting somewhere? what else can I try?


You may need to file a bug report for this. I’m not sure if the graphics driver plays some part here (with the backlight level). It may be that the kernel drivers need to be upgraded to cope with some BIOS change.

Anyway, I wonder if ‘xbacklight’ will play nicely with your screen brightness level adjustment?

The following command should return the current level (good for checking the effect of keys as well in terms of % increase or decrease)


To set half-brightness (assuming 100 is max)

xbacklight -set 50

Does this work OK?

Lovely command :smiley: this is the output and what I did (tried as root, as me and as the new user caf4926 recommend me to try…)

  1. FN+F2 until the brightness indicator goes to the left (lowest setting)
  2. xbacklight
  3. FN+F3 just one time (the screen brightness goes up a little as the indicator)
  4. xbacklight
  5. FN+F3 three times more (each time the indicator goes up one bit, and the screen brightness goes like high/low each time)
  6. xbacklight
  7. FN+F3 until the indicator goes to the highest level (if you keep pressed the FN+F3 keys the screen brightness blink like high/low, high/low, high/low, indefinitely…)
  8. xbacklight
  9. FN+F2 until de indicator goes to the lowest level (you get one blink high/low brightness and then it keeps in low brightness til the lowest level… so no blinking)
  10. xbacklight -set 50
  11. xbacklight
    (but the screen keeps my last brightness level… bright…)
  12. xbacklight -set 90, xbacklight -set 20, etc etc etc any setting I tried the brightness do not change. Anyway the xbacklight -get gives me the value I set.

Ohhh Shine on you crazy brightness… :-p

Should I place a bug report? (never did that, I’ll have to learn…)
Is there anywhere else to look for a config ~/.kde4/*?

Thanks for your time and help,

I don’t know why the BIOS upgrade broke your display brightness key functions, but since you’re using KDE 4.6.X, you could try taking advantage of the KDE Power Management System. This includes defining the keys that can increase and decrease display brightness. (It doesn’t even have to be the keys that your laptop uses by default).

Navigate to System Settings>>Shortcuts and Gestures>>Global Keyboard Shortcuts

You’ll see that there are ‘Actions’ for ‘Decrease Screen Brightness’ and ‘Increase Screen Brightness’. The associated ‘Global’ keys can be set there. Click on ‘Monitor Brightness Down’ for example, and select ‘Custom’ to add a custom key (which could be the same as your default key I guess). When the changes are made, click ‘Apply’. Can you now ramp up and down with the display brightness?

Just tried that, but :’(:’( same thing, I could create the new shortcuts ALT+CTRL+UP and DOWN keys.

The brightness indicator goes up and down with no change on the notebook brightness.

I will have to place a bug report as you told me (lets see how :slight_smile:

Thanks for you help and time!:slight_smile: