linux-kernel - Re: [Intel-gfx] 3.15-rc5: Regression in i915 driver?

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Date:	Sun, 18 May 2014 21:08:40 +0200
From:	Thomas Meyer <thomas@...3r.de>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Daniel Vetter <daniel.vetter@...ll.ch>,
	Dave Airlie <airlied@...il.com>,
	"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [Intel-gfx] 3.15-rc5: Regression in i915 driver?

Am Montag, den 12.05.2014, 07:33 +0100 schrieb Chris Wilson:
> On Sun, May 11, 2014 at 07:40:57PM +0200, Daniel Vetter wrote:
> > On Sun, May 11, 2014 at 11:02 AM, Dave Airlie <airlied@...il.com> wrote:
> > > On 11 May 2014 18:28, Thomas Meyer <thomas@...3r.de> wrote:
> > >> Hi,
> > >>
> > >> 3.14.3 works as expected.
> > >> 3.15-rc5 shows a strange behaviour: When resuming from ram the X server
> > >> seems to be disfunctional.
> > >>
> > >> I see this WARNING in the kernel log before suspend to ram in the early
> > >> boot process:
> > 
> > Doesn't ring a bell really.
> 
> Same symptoms as
> https://bugs.freedesktop.org/show_bug.cgi?id=76554
> -Chris
> 

bisected this to:
# first bad commit: [78f2975eec9faff353a6194e854d3d39907bab68] drm/i915: Move all ring resets before setting the HWS page

commit 78f2975eec9faff353a6194e854d3d39907bab68
Author: Chris Wilson <chris@...is-wilson.co.uk>
Date:   Wed Apr 2 16:36:07 2014 +0100

    drm/i915: Move all ring resets before setting the HWS page
    
    In commit a51435a3137ad8ae75c288c39bd2d8b2696bae8f
    Author: Naresh Kumar Kachhi <naresh.kumar.kachhi@...el.com>
    Date:   Wed Mar 12 16:39:40 2014 +0530
    
        drm/i915: disable rings before HW status page setup
    
    we reordered stopping the rings to do so before we set the HWS register.
    However, there is an extra workaround for g45 to reset the rings twice,
    and for consistency we should apply that workaround before setting the
    HWS to be sure that the rings are truly stopped.
    
    Reference: http://lkml.kernel.org/r/20140423202248.GA3621@amd.pavel.ucw.cz
    Tested-by: Pavel Machek <pavel@....cz>
    Cc: Naresh Kumar Kachhi <naresh.kumar.kachhi@...el.com>
    Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
    Reviewed-by: Jesse Barnes <jbarnes@...tuousgeek.org>
    Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
    Signed-off-by: Jani Nikula <jani.nikula@...el.com>

Reverting above commit from current linus' master tree makes the display server behave correctly after resume from ram.

with kind regards
thomas


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