Owain Ainsworth
0b5266ff64
On Mobile chipsets, we often enable PipeB instead of PipeA, but the test in here was insufficient, falling back to pipe A if the area intersection returned zero. Therefore, in the case where a window went off to the top of the left of the screen, it would freeze, waiting on the wrong vblank. Fix this mess by checking the sarea for a crtc being zero sized, and in that case always default to the other one.