Hi,

My brightness Fn keys (Fn+F4/F5) don't work for some reason, and I think the problem is in the kernel. I can set brightness with xbacklight, I can change key bindings to some other keys (e.g. to my current volume keys) and it will work (I'm using dwm, so key bindings are in config.h). Also I can adjust brightness in BIOS and GRUB with Fn+F4/F5.

Is there a kernel option for it? And if not, what else can be the problem?

Thank ye all.

Since you don't tell us what brand/model of laptop, running what version/distro of Linux, with what desktop environment...who knows??? We can't guess...provide details, and we may be able to help.

Alpine (written under my nick), 4.4.27, Dell Inspiron, dwm. I already posted another thread on hybrid graphics, where I mention all of that, so I thought I told it. Sorry about it.

You might try to install acpid and acpi-support. At least that's the debian package with features to change brightness on certain laptops. And other things like shutdown when the power button is pushed. Useful when the keyboard stops responding as that button still works most times and does a clean shutdown.

I have Debian with the same kernel config on another partition, it has acpid (current Alpine has acpi, kinda limited in features), no difference. Also tried with Openbox. And power button key works, to shutdown the machine I use only it.

Solved by remapping keys with xmodmap. My XF86MonBrightnessUp and XF86MonBrightnessDown were missing, so I made a custom .Xmodmap file in my home. Identified those keys with keycodes with xev.

Hello,

I had the same issue and found this post, so maybe others might be helped...

Running xubuntu 18.10 on a Dell Inspiron 17 7000 (7786).

The solution was to remove all the grub command line options except "acpi_backlight=vendor":
sudo nano /etc/default/grub
Edit the GRUB_CMDLINE_LINUX_DEFAULT line as follows:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
Run: sudo update-grub
Run: sudo reboot now

Previously, I had tried the following option without success:
"acpi_osi=! "acpi_osi=Windows 2015""
"nomodeset" (this was needed until I installed the latest nvidia driver)
"acpi_osi="
"acpi_osi=Linux"


Without success meant the Fn+F11 and Fn+F12 keys did nothing, and none of these commands worked...
ls -l /sys/class/backlight
Now, it shows "dell_backlight intel_backlight"

Running this gave nothing either:
xrandr --verbose | grep Bright
Now it shows " Brightness: 1.0".

The other function keys - volume, keyboard backlight, wireless on/off, etc... were working OK.

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