So I updated with your patches and had mainline nouveau with the patched X server. It does hang the system very quickly. Sometimes already when starting lightdm, most often right after typing the password, sometimes logging in is possible, but it will hang very quickly. With gnurou's nouveau it worked stable in gnome3 and xfce. mesa and drm from gnurou seems to be a bit old... Maybe I look later.
I can't get wifi to work at all anymore in arch. In chrome os it works fine, but rebooting to arch it looks just like the hardware isn't there at all. Also bluetooth doesn't work, I guess, it's the same. Time to try a build of only the module and adding some printk statements again to see where it fails *sigh*
Also linux-armv7-rc 4.5 is in the repository, so I'm going to try that too