This bug is a duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/776999
I can confirm the following workaround allows full brightness control:
nox2apic kernel param
AND
In Device section of xorg.conf:
Option "RegistryDwords" "EnableBrightnessControl=1"
This bug is a duplicate of https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/776999
I can confirm the following workaround allows full brightness control:
nox2apic kernel param
AND
In Device section of xorg.conf:
Option "RegistryDwords" "EnableBrightne ssControl= 1"