KDM does not initialize support for keyboard backlight at first attempt. LightDM works fine though. There's a somewhat related thread on KDE forum by Jens Reuterberg: http://forum.kde.org/viewtopic.php?f=66&t=118366 Steps to reproduce: 1. Log in using KDM 2. See that keyboard backlight is not detected at all, and cannot be changed nor by power management GUI, neither by Fn keys (but can be changed by "cat x > /sys/devices/platform/asus-nb-wmi/leds/asus::kbd_backlight/brightness" 3. Log out and log in using KDM 4. Everything works fine Actual result: Keyboard backlight is not detected and thus can't be changed, unless user relogins. Expected result: Keyboard backlight is functioning and adjustable upon session startup Rerproductible: Always Additional info: LightDM works perfect, backlight starts working right after logging in. Tested on Asus Zenbook UX21A. There's a related thread on KDE forum by Jens Reuterberg about laptop from the same series (UX31VD): http://forum.kde.org/viewtopic.php?f=66&t=118366
I use Debian sid with KDE 4.13.1 and I face the same issue. It annoys me a lot! I didn't try other DMs, though. My laptop is ASUS N750.
I have the same issue, also running Debian testing with KDE 4.13.x. My laptop is an Asus G55VW. I have narrowed the issue and found a workaround. A summary is available from: https://bugs.debian.org/754200 or https://forum.kde.org/viewtopic.php?f=63&t=121045 I haven't tried lightdm, but the bottom line is KDM does NOT start upowerd early enough for powerdevil to become aware of the keyboard brightness capabilities. The workaround is to put a script in ~.kde/env/ calling qdbus to start upowerd.
Exactly the same issue with KDE-4.14.2, in Debian Testing/Unstable installed on Asus G56JK. Andres's workaround works for me (an sh script in ~/.kde4/env/, which runs "qdbus --system org.freedesktop.UPower"). I haven't tried other DMs.
Same issue with a macbook pro late 2013 running fedora 21 (with SDDM as login manager). Login out and login in brings the keyboard backlight support back. The keyboard backlight keys used to work with a previous version of kde (unfortunately I can't tell exactly which version as I didn't notice when the issue started to appear)
I double checked, and my fedora 21 still use kdm as login manager
Since kdm has been discontinued, I mark this bug RESOLVED WONFIX.