i915 irq storm mitigation in 3.10

[Jan Niggemann <jn@hz6.de>]

Hi list,

I'm not sure, but I think the recent patch to keep i915 systems from 
locking up / slowing down in case of irq storms didn't fully help.
I compiled 3.10, but every now and then, my system has the same 
symptoms as before.

grep storm /var/log/messages
Jul  5 21:55:43 muretop kernel: [  324.767375] [drm] HPD interrupt 
storm detected on connector DP-3: switching from hotplug detection to 
polling
Jul  6 23:05:57 muretop kernel: [  200.372208] [drm] HPD interrupt 
storm detected on connector HDMI-A-1: switching from hotplug detection 
to polling
Jul  6 23:07:51 muretop kernel: [  313.752039] [drm] HPD interrupt 
storm detected on connector DP-3: switching from hotplug detection to 
pol

I notice up to 50% CPU from kworker/u8:0 when my system slows down.

I'm new to kernel development, but if you tell me what to do, I'm very 
willing to help diagnosing this.

Regards
jan