http://websvn.kde.org/trunk/KDE/kdebase/workspace/libs/solid/control/powermanager.cpp?r1=1062504&r2=1069849&pathrev=1069849
https://bugs.kde.org/show_bug.cgi?id=219333#c23

--- libs/solid/control/powermanager.cpp
+++ libs/solid/control/powermanager.cpp
@@ -155,7 +155,7 @@
     if(device.isEmpty())
     {
         Solid::Control::PowerManager::BrightnessControlsList controls = brightnessControlsAvailable();
-        if(controls.size() == 0)
+        if(controls.keys(Solid::Control::PowerManager::Screen).isEmpty())
         {
 #ifdef Q_WS_WIN
             return false;
@@ -185,7 +185,7 @@
     if(device.isEmpty())
     {
         Solid::Control::PowerManager::BrightnessControlsList controls = brightnessControlsAvailable();
-        if(controls.size() == 0)
+        if(controls.keys(Solid::Control::PowerManager::Screen).isEmpty())
         {
 #ifdef Q_WS_WIN
             return false;