From: Eric Anholt <eric@anholt.net>
To: "Rafael J. Wysocki" <rjw@sisk.pl>, Zhenyu Wang <zhenyuw@linux.intel.com>,
       Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Cc: linux-pm@lists.linux-foundation.org, dri-devel@lists.sourceforge.net,
       Kernel Testers List <kernel-testers@vger.kernel.org>,
       Jesse Barnes <jbarnes@virtuousgeek.org>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] i915 / PM: Fix crash while aborting hibernation (Re:
 [linux-pm] [regression] "drm/i915: implement new pm ops" disables irq on
 aborted s2disk)
In-Reply-To: <201002072148.24588.rjw@sisk.pl>
References: <4B695BA0.4000007@tuffmail.co.uk>
	<201002032344.41915.rjw@sisk.pl>
	<20100204013157.GA30011@zhen-devel.sh.intel.com>
	<201002072148.24588.rjw@sisk.pl>
Date: Wed, 10 Feb 2010 16:59:59 -0800
Message-ID: <87k4ukd1tc.fsf@pollan.anholt.net>
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On Sun, 7 Feb 2010 21:48:24 +0100, "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> On Thursday 04 February 2010, Zhenyu Wang wrote:
> > On 2010.02.03 23:44:41 +0100, Rafael J. Wysocki wrote:
> > > On Wednesday 03 February 2010, Alan Jenkins wrote:
> > > > Hi
> > > >=20
> > > > I found this regression on my EeePC 701 with modesetting enabled.  =
When=20
> > > > I hibernate using s2disk, I can abort the hibernation by pressing t=
he=20
> > > > backspace key.  Doing so breaks X on 2.6.32-rc6 (but not 2.6.32).
> > >=20
> > > Yeah.
> > >=20
> > > To be honest, I knew that's going to happen, but didn't have the time=
 to take
> > > care of it.
> > >=20
> > > The problem is that i915 does literally _nothing_ in its .thaw() call=
back,
> > > although it should at least reverse whatever .freeze() did to the har=
dware
> > > (and memory allocations and so on), so that the adapter is functional
> > > after creating the image.
> > >=20
> > > Fixing this requires some thought, though, because at the moment .fre=
eze()
> > > thinks it's .suspend(), which is not the case as this report clearly =
shows.
> > > So, in fact i915_pci_suspend() has to be split into the .freeze() par=
t and
> > > the poweroff part cleanly and that's not  so simple (at least to me).
> > >=20
> >=20
> > Right, I think that'll be more clean, stuff in i915_save/restore_state(=
) need
> > to be splited too, especially isolate stuff for mode setting and other =
device
> > state, as what my original purpose for this is to remove extra mode set=
ting=20
> > cycle in old behavior so not waste time for hibernate.
>=20
> We can't really do that, because we'll need to restore the saved state at=
 the
> resume-from-hibernation stage.
>=20
> The appended patch fixes the issue for me, although it's been only tested
> a little.  It sort of defeats the purpose of commit
> cbda12d77ea590082edb6d30bd342a67ebc459e0, but I don't see any less invasi=
ve
> way to fix this except maybe for reverting that commit entirely.
>=20
> Note that the drm_irq_[un]install() thing may be unnecessary, but I wasn'=
t sure
> about that and surely wouldn't suggest doing that for 2.6.33.  Also it lo=
oks like
> some things from the freeze and thaw parts may be moved to the "low-level"
> suspend and resume parts, respectively, but that would require some
> i915_gem_* surgery I was too scared to do.
>=20
> Alan, please test, i915 guys, please review.
>=20
> Rafael

Applied to for-linus.  Thanks!

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