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From:   Martin Steigerwald <martin@lichtvoll.de>
To:     Ville =?ISO-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Intel Gfx Mailing List <intel-gfx@freedesktop.org>,
        Thorsten Leemhuis <regressions@leemhuis.info>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [Intel-gfx] [REGRESSION 4.19-rc2] sometimes hangs with black screen when resuming from suspend or hibernation (was: Re: Linux 4.19-rc2)
Date:   Wed, 12 Sep 2018 23:03:55 +0200
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In-Reply-To: <20180912171020.GE5565@intel.com>
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Ville Syrjälä - 12.09.18, 19:10:
> On Tue, Sep 11, 2018 at 12:17:05PM +0200, Martin Steigerwald wrote:
> > Cc´d Intel Gfx mailing list, in case somebody there knows something:
> > 
> > Cc´d Thorsten for regression tracking… forgot initially. Can also
> > open bug report at a later time but so far I cannot provide many
> > details about the issue.
> > 
> > Rafael J. Wysocki - 11.09.18, 10:17:
> > > On Tue, Sep 11, 2018 at 10:01 AM Martin Steigerwald
> > 
> > <martin@lichtvoll.de> wrote:
> > > > Hi.
> > > > 
> > > > Linus Torvalds - 02.09.18, 23:45:
> > > > > As usual, the rc2 release is pretty small. People are taking a
> > > > 
> > > > With 4.19-rc2 this ThinkPad T520 with i5 Sandybrdige sometimes
> > > > hangs
> > > > with black screen when resuming from suspend or hibernation. 
> > > > With
> > > > 4.18.1 it did not. Of course there have been userspace related
> > > > updates that could be related.
> > > > 
> > > > I currently have no time to dig into this and on this production
> > > > laptop I generally do not do bisects between major kernel
> > > > releases.
> > > > So currently I only answer questions that do not require much
> > > > time
> > > > to answer.
> > > > 
> > > > For now I switched back to 4.18. If that is stable – and thus
> > > > likely
> > > > no userspace component is related –, I go with 4.19-rc3 or
> > > > whatever
> > > > is most recent version to see if the issue has been fixed
> > > > already.
> > > 
> > > There were almost no general changes related to system-wide PM
> > > between 4.18 and current, so I would suspect one of the device
> > > drivers or the x86 core.  It also may be something like CPU
> > > online/offline, however.> 
> > I see. I wondered about intel-gfx driver already. Of course it could
> > also be something else.
> > 
> > I forgot to mention: The mouse pointer was visible, but the screen
> > remained black.
> 
> Did the mouse cursor still move or not?

No, it did not move.

> Could also try suspend without any GUI stuff in the way. Or try the
> intel ddx instead of the modesetting ddx (assuming that's what
> you're using now) and no compositor to rule out GPU hangs killing
> the compositor. The intel ddx can also deal with the GPU not
> recovering from a hang by switching to software rendering,
> whereas modesetting cannot.

Thanks for these suggestions. Currently laptop is still on 4.18 again 
(4.18.7) and I did not see this hang after resume so far. If it 
continues to be stable for a few more days, I try with latest 4.19 again 
as then its very likely kernel related.

> Hmm. Also T520 is an optimus laptop maybe? If there's an nvidia
> GPU involved it's going to be hard to get anyone to care. Better
> switch that off in the BIOS if you haven't already.

I decided back then for Intel only graphics. I never regretted this.

For me NVidia graphics is not an option, unless NVidia significantly 
changes their policy regarding free software drivers.

Thanks,
-- 
Martin