[Intel-gfx] 'Timed out waiting for forcewake old ack to clear' and hangup on IvyBridge system

[Guenter Roeck]

Hi all,

after upgrading one of my servers to 3.8, then 3.9.7 and 3.10-rc6, I started to
see lots of "Timed out waiting for forcewake old ack to clear" error messages,
including hang-ups especially if the system was highly loaded. With 3.5.24
everything was fine.

After backing out commit 36ec8f877 (drm/i915: unconditionally use mt forcewake
on hsw/ivb), everything is back to normal. The log message is still there, but
only once during boot, and the system runs stable.

CPU is "Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz", mainboard is Supermicro
C7H61, BIOS version 2.00 dated 11/02/2012. Configuration file is whatever
comes with Ubuntu; I'll be happy to provide a copy if anyone thinks it might
help.

Any idea what else I can do besides using a special kernel with the backed out
commit ? Is it possible that others have the same problem ?

Thanks,
Guenter