https://bugs.freedesktop.org/show_bug.cgi?id=49943
--- Comment #3 from Harald Judt h.judt@gmx.at 2012-05-20 05:05:10 PDT --- Changing the register value using radeonreg also doesn't work:
radeonreg regset 0x6058 0x00000000 OLD: 0x6058 (6058) 0xff0ff000 (-15732736) NEW: 0x6058 (6058) 0xff0ff000 (-15732736)