[Intel-gfx] i915: hotplug events gone wild

[Andrew Lutomirski]

On Sat, Jan 30, 2010 at 10:02 PM, Andrew Lutomirski <luto at mit.edu> wrote:
> [I posted this bug earlier with a terrible description as "resume
> lagginess and other problems."  Here it is again with a better bug
> report.]
>
> I'm running 2.6.33-rc5 (plus some wireless-testing stuff, but I've
> seen this problem on a variety of 2.6.33-rc? kernels).  Every now and
> then, X starts to lag badly on my GM45 laptop.  When this happens, I
> usually see a bunch of events in udevmonitor.  Running with
> drm.debug=0x02 (and the patch below to keep the log under control), I
> see tons of messages like this:
>
> [41210.355059] [drm:i915_driver_irq_handler], hotplug event received,
> stat 0x28200000

I can't really debug the driver code, since none of the hotplug stuff
appears to be documented.  Interrupt bit 17
(I915_DISPLAY_PORT_INTERRUPT in i915_reg.h) is shown as reserved in
the docs (vol 1a), and I can't find documentation for
PORT_HOTPLUG_STAT at all, other than the fact that it exists.

--Andy