linux-kernel - Re: Intel 82915G/GV/910GL, 2.6.36.2: problem with CONFIG_DRM_I915

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Date:	Fri, 17 Dec 2010 01:15:31 +0000
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Dave Airlie <airlied@...il.com>, Harald Dunkel <harri@...ics.de>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Intel 82915G/GV/910GL, 2.6.36.2: problem with CONFIG_DRM_I915_KMS=y

On Fri, 17 Dec 2010 10:01:26 +1000, Dave Airlie <airlied@...il.com> wrote:
> (cc'ing Chris).
> 
> On Fri, Dec 17, 2010 at 8:23 AM, Harald Dunkel <harri@...ics.de> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Hi folks,
> >
> > according to http://bugs.debian.org/607300 I have to rebuild 2.6.36.2
> > with CONFIG_DRM_I915_KMS=y. Problem:
> >
> > At boot time I get a message "waiting for /dev to be fully populated",
> > then the screen goes blank and the monitor enters power save mode.
> > 2.6.36.2 without CONFIG_DRM_I915_KMS didn't show this problem.
> >
> > My grub2 configuration says
> >
> >        GRUB_GFXMODE=1280x1024
> >        GRUB_GFXPAYLOAD_LINUX="keep"
> >
> > If I comment out these 2 lines and rebuild grub.cfg, then the problem
> > goes away, too. I just get a 80x25 display for grub in this case.
> >
> 
> Is this a regression since 2.6.36 or 2.6.35?

Sounds like:

commit 47f1c6c9ffdec0c0e5a2c2709bd63c7380b325c4
Author: Chris Wilson <chris@...is-wilson.co.uk>
Date:   Fri Dec 3 15:37:31 2010 +0000

    drm/i915: Clean conflicting modesetting registers upon init
    
    If we leave the registers in a conflicting state then when we attempt
    to teardown the active mode, we will not disable the pipes and planes
    in the correct order -- leaving a plane reading from a disabled pipe and
    possibly leading to undefined behaviour.
    
    Reported-and-tested-by: Andy Whitcroft <apw@...onical.com>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=32078
    Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
    Cc: stable@...nel.org

which was prompted by an investigation as to why grub2 was causing a
modesetting failure.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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