Backlight control does not work and there are no entries in /sys/class/backlight. When I boot my system with the option GRUB_CMDLINE_LINUX_DEFAULT="acpi_backlight=vendor" I can change the brightness with the command xrandr on a terminal. I attach all the system information about this problem. ls /sys/class/backlight > (it's void) grep -r . /proc/acpi > acpi sudo acpidump -o acpidump.txt sudo fwts > fwts sudo fwts method > fwts_method sudo dmidecode > dmidecode.log
Created attachment 140104 [details] grep -r . /proc/acpi > acpi
Created attachment 140105 [details] sudo acpidump -o acpidump.txt
Created attachment 140106 [details] sudo fwts > fwts
Created attachment 140107 [details] sudo fwts method > fwts_method
Created attachment 140108 [details] sudo dmidecode > dmidecode.log
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