Description:

xbacklight can be used to retrieve and set the backlight when xorg is started. After some time (less than 3h), the support vanishes and xbacklight does not display the brightness anymore nor can set it.

After restarting xorg, it works again for some time.

The problem occurs on Intel Skylake / Lenovo X1 Carbon Gen 4.



Additional info:
* package version(s)
* config and/or log files etc.


Steps to reproduce:
[20:46] feder:asl% pacman -Q | grep -e xorg -e intel -e "^linux "
linux 4.8.8-1
xf86-video-intel 1:2.99.917+730+gdad64e9-1
xorg-appres 1.0.4-1
xorg-bdftopcf 1.0.5-1
xorg-font-util 1.3.1-1
xorg-font-utils 7.6-4
xorg-fonts-alias 1.0.3-1
xorg-fonts-encodings 1.0.4-4
xorg-fonts-misc 1.0.3-4
xorg-luit 1.1.1-2
xorg-mkfontdir 1.0.7-2
xorg-mkfontscale 1.1.2-1
xorg-server 1.18.4-1
xorg-server-common 1.18.4-1
xorg-setxkbmap 1.3.1-1
xorg-xauth 1.0.9-1
xorg-xbacklight 1.2.1-1
xorg-xdpyinfo 1.3.2-1
xorg-xev 1.2.2-1
xorg-xinit 1.3.4-4
xorg-xinput 1.6.2-1
xorg-xkbcomp 1.3.1-1
xorg-xkill 1.0.4-1
xorg-xmodmap 1.0.9-1
xorg-xrandr 1.5.0-1
xorg-xrdb 1.1.0-2
xorg-xset 1.2.3-1
xorg-xsetroot 1.1.1-2
xorg-xwd 1.0.6-1
xorg-xwininfo 1.1.3-1
[20:46] feder:asl% uname -a
Linux feder 4.8.8-1-ARCH #1 SMP PREEMPT Tue Nov 15 08:25:24 CET 2016 x86_64 GNU/Linux
[20:46] feder:asl% xbacklight
[20:46] feder:asl% cat /sys/class/backlight/intel_backlight/brightness
511
[20:46] feder:asl%