Also i can't compile with cmake .. -DHAVE_DDCUTIL=ON
/home/toni/powerdevil/daemon/backends/upower/ddcutilbrightness.cpp:39:5: error: ‘ddca_get_display_info_list2’ was not declared in this scope
ddca_get_display_info_list2(true, &dlist);
headers are missing. I've installed ddcutil.