no control for screen brightness

Dear all,

I have a lenovo ideapad P400. F11 and F12 buttons are also buttons for  screen brightness; in thesis, the function buttons (F11 and F12) should  be called at pressing the Fn button at the bottom of the keyboard, so the default for theses buttons is to adjust brightness.

But this screen brightness control does not work at openSuSE 15.1 (I cannot  say when this started as I normally use at full brightness - an it was so!). As a matter of fact, booting at the default  linux makes the screen completely dark; a workaround is to boot into  linux security mode, which gives me mid brightness, but in any case,  after boot option is chosen, controls for brightness do not work  (either pressing Fn or not). They seem to work during grub presenting  the options for system booting, but once linux is selected, no way to  control the brightness, therefore, they (brightness) seem to be fixed (at a certain value) then  (id est, completely dark for default linux and mid brightness at linux security  mode). 

Where should I check to solve this? This seemed to work at Leap 42.3. Ah, xbacklight (as root) outputs " No outputs have backlight property".

Thanks, 

Jorge

I’m getting


xbacklight
No outputs have backlight property

too.

Leap 15.1, icewm

Hi
You might have to look at acpi boot option eg


acpi_osi=\"!Windows 2012\"

There are many other options, see https://www.kernel.org/doc/Documentation/admin-guide/kernel-parameters.txt

For a friend who had problems with the brightness control (only available in Windows), I found that xrandr worked fine.

xrandr -q

reveals the monitor name.

xrandr --output <monitor name> --brightness <n>

where <n> is a value from 0 to 1 sets the brightness.