[Intel-gfx] [PATCH] drm/i915: Undo gtt scratch pte unmapping again

[Takashi Iwai]

At Thu, 27 Mar 2014 07:55:57 +0100,
Daniel Vetter wrote:
> 
> On Thu, Mar 27, 2014 at 7:41 AM, Takashi Iwai <tiwai at suse.de> wrote:
> >> It apparently blows up on some machines. This functionally reverts
> >>
> >> commit 828c79087cec61eaf4c76bb32c222fbe35ac3930
> >> Author: Ben Widawsky <benjamin.widawsky at intel.com>
> >> Date:   Wed Oct 16 09:21:30 2013 -0700
> >>
> >>     drm/i915: Disable GGTT PTEs on GEN6+ suspend
> >>
> >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=64841
> >> Reported-and-Tested-by: Brad  Jackson <bjackson0971 at gmail.com>
> >> Cc: stable at vger.kernel.org
> >> Cc: Takashi Iwai <tiwai at suse.de>
> >> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> >> Cc: Todd Previte <tprevite at gmail.com>
> >> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> >
> > The commit was the fix for the memory corruption and lock up at S4 on
> > some (Haswell) machines.  This revert will re-introduce the issue
> > again very likely.  I'm going to check with the latest tree, but this
> > may take some time.
> >
> > Wouldn't it be safer to revert this conditionally like I suggested in
> > comment 10 of the bugzilla entry?
> 
> I know that this will blow up, but apparently no one from our side
> really bothered to test stuff or work on this. So regression wins and
> I've pushed out the revert - this bug has been lingering a bit too
> long.

Well, the problem is rather that no one who worked on the HSW S4 fix
(including me) could reproduce the regression on SNB machines.
Have you seen any similar report with gen7 or newer?


Takashi