Bug 20296

Summary:	vblank interrupts at startup after kernel upgrade (2.6.28)
Product:	xorg	Reporter:	Alberto González <luis6674>
Component:	Driver/intel	Assignee:	Jesse Barnes <jbarnes>
Status:	RESOLVED FIXED	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium
Version:	7.4 (2008.09)
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Alberto González 2009-02-24 09:02:25 UTC

After upgrading to kernel 2.6.28 I see about 60-100 extra wakeups as reported by Powertop coming from i915@pci... interrupts (the problem doesn't happen with kernel 2.6.27).

It happens on my two machines using Intel graphics (a 5 year old Pentuim 4 using i845G chipset and new Core 2 Duo using G45 chip).

It only happens when booting directly into X. If I bootup to console and start X manually, no problem. Also th problem goes away switching to console and back to X (or suspending to disk or RAM and waking up).

References:
http://bugzilla.kernel.org/show_bug.cgi?id=12337
http://marc.info/?l=linux-kernel&m=123547283726418&w=2

I'm using xserver-1.5.3 and xf86-video-intel-2.4.3.

Comment 1 Alberto González 2009-02-24 11:05:44 UTC

I upgraded to xf86-video-intel 2.6.1 (also had to upgrade liddrm to 2.4.5 and install libpthread-stubs) and the problem persisted (about 140 wakeups this time).

Switching to console and trying to go back to X hard locked the system, so I can't verify the problem goes away doing so.

Comment 2 Alberto González 2009-03-14 15:29:32 UTC

A small update: I just tested using UXA (instead of EXA) and that makes the problem disappear.

Comment 3 Jesse Barnes 2009-03-30 17:24:17 UTC

Since EXA probably won't be supported going forward, I'll close this out as fixed since UXA doesn't have the problem.  Thanks for reporting.

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