[Intel-gfx] [regression?] i915 generating wakeups even when idle

[Andrew Lutomirski]

On Tue, Dec 7, 2010 at 5:13 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Tue, 7 Dec 2010 16:31:24 -0500, Andrew Lutomirski <luto at mit.edu> wrote:
>> On Tue, Dec 7, 2010 at 4:03 PM, Andrew Lutomirski <luto at mit.edu> wrote:
>> > Hi all-
>> >
>> > Somewhere between Fedora 13 (with 2.6.35, I think) and Fedora 14 +
>> > 2.6.36.1, i915 started generating exactly 50 interrupts per second
>> > (suspiciously equal to my refresh rate) when X is running.  I have the
>> > Xorg driver 2.12.0 (specifically
>> > xorg-x11-drv-intel-2.12.0-6.fc14.1.x86_64).  When I switch to a text
>> > console but leave X running, the interrupts stop.
>> >
>> > Any ideas what to look at?
>>
>> Quitting compiz fixes it.  Suspending compiz also fixes it.
>
> So it is the vblank interrupt. The vblank interrupt is get alive for a few
> seconds after the last use. If it keeps going, then either the system is
> as idle as you believe or we lost track of the last user and forget to
> switch off the interrupt.
>
> drm.debug=0xf (echo 0xf > /sys/module/drm/parameters/debug) will have the
> gory details of who/when triggers the vblank interrupt.

Will do tomorrow.  I'm currently hampered by:

 47:       9073       9455   PCI-MSI-edge      <A0>Bs3^A<88><FF><FF>

in /proc/interrupts after a reboot (I *think*, but I'm not entirely
sure, that that's supposed to be i915).

--Andy