Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <1562875878.2840.0.camel@HansenPartnership.com>
Subject: Re: screen freeze with 5.2-rc6 Dell XPS-13 skylake  i915
From:   James Bottomley <James.Bottomley@HansenPartnership.com>
To:     Chris Wilson <chris@chris-wilson.co.uk>,
        intel-gfx@lists.freedesktop.org
Cc:     linux-kernel <linux-kernel@vger.kernel.org>
Date:   Thu, 11 Jul 2019 13:11:18 -0700
In-Reply-To: <156283735757.12757.8954391372130933707@skylake-alporthouse-com>
References: <1561834612.3071.6.camel@HansenPartnership.com>
         <156283735757.12757.8954391372130933707@skylake-alporthouse-com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 2019-07-11 at 10:29 +0100, Chris Wilson wrote:
> Quoting James Bottomley (2019-06-29 19:56:52)
> > The symptoms are really weird: the screen image is locked in
> > place.  The machine is still functional and if I log in over the
> > network can do anything I like, including killing the X server and
> > the display will never alter.  It also seems that the system is
> > accepting keyboard input because when it freezes I can cat
> > information to a file (if the mouse was over an xterm) and verify
> > over the network the file contents. Nothing unusual appears in
> > dmesg when the lockup happens.
> > 
> > The last kernel I booted successfully on the system was 5.0, so
> > I'll try compiling 5.1 to narrow down the changes.
> 
> It's likely this is panel self-refresh going haywire.
> 
> commit 8f6e87d6d561f10cfa48a687345512419839b6d8
> Author: José Roberto de Souza <jose.souza@intel.com>
> Date:   Thu Mar 7 16:00:50 2019 -0800
> 
>     drm/i915: Enable PSR2 by default
> 
>     The support for PSR2 was polished, IGT tests for PSR2 was added
> and
>     it was tested performing regular user workloads like browsing,
>     editing documents and compiling Linux, so it is time to enable it
> by
>     default and enjoy even more power-savings.
> 
> Temporary workaround would be to set i915.enable_psr=0

It looks plausible.  I have to say I was just about to mark a bisect
containing this as good, but that probably reflects my difficulty
reproducing the issue.

James