Okay so with the latest patches it seems to successfully boot with dpm=1 much
more often (I would say 1/4 times) while before it was almost never. Again
that's without changing anything between boots and without aspm=0.

Same remarks than my previous post however, it seems it can't reach power level
2 even when forcing high power level and performance mode. Another issue is
that the display gets completely garbled
(http://wstaw.org/m/2013/07/27/IMG_20130727_090107.jpg) when trying to set
battery power mode until the GPU soft resets or that I set it back to
"balanced" or "performance". Here is what is thrown into dmesg when this
happens (sorry couldn't paste it since X was totally unresponsive) :
http://wstaw.org/m/2013/07/27/IMG_20130727_095805.jpg