Hitting a bug ?
Be sure to test on this version of Mesa first: https://github.com/iXit/Mesa-3D/

Here is the list of known bugs:
  * Emulated fog behaviour not implemented (old games only)
  * Fixed function pipeline has a few bugs
  * Stateblocks have some bugs (CIV IV: black textures, etc)
  * Minor graphical error(road texture in payday2. Red shadows on Unreal Engine games)
  * Bad window messages behavior (causes some games to not start)
  * Red shadows on Unreal Engine Games for radeon. We have no way to solve this bug (we'll need help from AMD).

Wish to help debug ? Come on our irc channel
Or report here: https://github.com/iXit/Mesa-3D/issues?