FYI I see a similar GPU stalls/display blanks with an upgrade from 10.1.4 ->
10.2.1. I am on Verde with VERDE_mc2.bin.

I started bisecting, but it takes me about a day to judge good vs bad, and as I
have around 1000 commits in front of me, this will take about 10 days.

I am also on Arch. xorg-server=1.15.1, xf86-video-ati=7.3.0. linux=3.15.2.