Re: kernel 2.6.37-rc2 breaks i915 graphics

[Chris Vine <chris@cvine.freeserve.co.uk>]

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On Sun, 21 Nov 2010 10:30:43 +0000
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> On Sun, 21 Nov 2010 10:23:44 +0000, Chris Vine
> <chris@cvine.freeserve.co.uk> wrote:
> > Hi,
> > 
> > With kernel 2.6.37-rc2, i915 graphics usually fails on boot-up after
> > modesetting with my Lenovo S12 netbook which uses the Intel 945GME
> > Express Integrated Graphics Controller.  It displays up to the
> > point at which modesetting takes place and then usually goes blank.
> > 
> > There may be some kind of race at work here: first, sometimes
> > (maybe 1 times in 4) graphics comes up correctly on a first cold
> > boot, but I have never managed to get it to come up on a warm
> > reboot. Secondly, graphics can be restored when I know (but cannot
> > see) that boot-up has concluded, simply by suspending the laptop
> > and then resuming.  Resuming the laptop after a suspend always
> > brings up the graphics correctly.
> 
> Add drm.debug=0xe to your boot commandline and compare if there is any
> difference between a successful cold boot, a broken cold boot and a
> warm boot. Similarly, comparing the output of intel_reg_dumper after
> each should yield a few clues as to what stage in the boot process we
> fail. -Chris

First an additional datum point: 2.6.37-rc1 works normally, so the bug
is something introduced between 2.6.37-rc1 and 2.6.37-rc2 (to that
extent it may be related to this bug which reports a similar phenomenon:
http://lkml.org/lkml/2010/11/21/23 ).

Attached is the dmesg output from a successful cold boot with
2.6.37-rc2, an unsuccessful cold boot and an unsuccessful warm boot,
each with drm.debug=0xe.

I can't provide the output of intel_reg_dumper:  I can't compile the
latest intel-gpu-tools from git (missing declaration/definition of
I915_EXE_BLT).  Probably something in a relevant library is too old.

Chris

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