Bug 23762

Summary: kernel 2.6.37-rc2 breaks i915 graphics
Product: Drivers Reporter: Maciej Rutecki (maciej.rutecki)
Component: Video(DRI - Intel)Assignee: drivers_video-dri-intel (drivers_video-dri-intel)
Status: CLOSED CODE_FIX    
Severity: normal CC: chris, chris, maciej.rutecki, rjw
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 2.6.37-rc2 Subsystem:
Regression: Yes Bisected commit-id:
Bug Depends on:    
Bug Blocks: 21782    

Description Maciej Rutecki 2010-11-25 20:10:44 UTC 
Subject    : kernel 2.6.37-rc2 breaks i915 graphics
Submitter  : Chris Vine <chris@cvine.freeserve.co.uk>
Date       : 2010-11-21 10:23
Message-ID : 20101121102344.7c590b99@laptop.homenet
References : http://marc.info/?l=linux-kernel&m=129033505414671&w=2

This entry is being used for tracking a regression from 2.6.36. Please don't
close it until the problem is fixed in the mainline.
Comment 1 Rafael J. Wysocki 2010-12-06 22:26:12 UTC 
On Saturday, December 04, 2010, Chris Vine wrote:
> On Fri,  3 Dec 2010 00:41:46 +0100 (CET)
> "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> > This message has been generated automatically as a part of a summary
> > report of recent regressions.
> > 
> > The following bug entry is on the current list of known regressions
> > from 2.6.36.  Please verify if it still should be listed and let the
> > tracking team know (either way).
> > 
> > 
> > Bug-Entry   : http://bugzilla.kernel.org/show_bug.cgi?id=23762
> > Subject             : kernel 2.6.37-rc2 breaks i915 graphics
> > Submitter   : Chris Vine <chris@cvine.freeserve.co.uk>
> > Date                : 2010-11-21 10:23 (12 days old)
> 
> Yes, it should still be in the list of regressions.  The bug is still
> present in kernel 2.6.37-rc4.
Comment 2 Chris Wilson 2010-12-16 14:29:28 UTC 
Sounds related to:

commit 47f1c6c9ffdec0c0e5a2c2709bd63c7380b325c4
Author: Chris Wilson <chris@chris-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@canonical.com>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=32078
    Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
    Cc: stable@kernel.org
Comment 3 Chris Wilson 2010-12-16 14:30:05 UTC 
But there is insufficient information to ascertain what is happening.
Comment 4 Chris Vine 2010-12-16 15:57:08 UTC 
Comment #2: The bug was not fixed by a commit of 3 December, unless it did not get into Linus's tree until after 2.6.37-rc5, but it is fixed in 2.6.37-rc6, so it may be something else.  (My e-mail to you of 21 November indicated that the bug was introduced between 2.6.37-rc1 and 2.6.37-rc2, if that helps.)

Comment #3: My e-mail to you of 21 November ( http://marc.info/?l=linux-kernel&m=129036448009024&w=2 ) provided what you had earlier asked for, and the original bug report contained some other information which you can see at the link provided by Rafael.  What additional information would you like?
Comment 5 Chris Wilson 2010-12-16 16:05:41 UTC 
Sorry, missed the reply. Had I searched my inbox for the msg-id, I would have your replies, which do indicate similar symptoms that prompted that patch.

That was merged into linus/master:

commit 6dde39be39e636c1d41e73590668d5903b11535b
Merge: f8f5d4f 599bbb9
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed Dec 8 06:34:39 2010 -0800