'Timed out waiting for forcewake old ack to clear' and hangup on IvyBridge system

[Guenter Roeck]

On Sat, Jun 22, 2013 at 12:16:46PM -0700, Jesse Barnes wrote:
> On Fri, 21 Jun 2013 23:58:08 -0700
> Guenter Roeck <linux at roeck-us.net> wrote:
> 
> > 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 ?
> 
> Ouch, so a BIOS that uses the other forcewake mechanism seems to have
> escaped.  Is there a newer one available for your system?  I'm hoping
> it'll fix the issue, otherwise we may have to introduce both methods
> for IVB again...
> 
I installed the latest BIOS version (2.00b), but it did not fix the problem.

Is there some info (such as an Intel document describing what needs to be done)
which I could pass on to Supermicro ?

I think it would be helpful if the condition was detected and reported, if that
is possible. I spent two days so far tracking this down. It would be nice
if others would not have to go through the same experience.

Thanks,
Guenter