Re: [Intel-gfx] screen freeze with 5.2-rc6 Dell XPS-13 skylake i915

From: "Souza, Jose" <jose.souza@intel.com>
To: "James.Bottomley@HansenPartnership.com" 
	<James.Bottomley@HansenPartnership.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"chris@chris-wilson.co.uk" <chris@chris-wilson.co.uk>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Intel-gfx] screen freeze with 5.2-rc6 Dell XPS-13 skylake i915
Date: Thu, 11 Jul 2019 20:25:19 +0000	[thread overview]
Message-ID: <27a5b2ca8cfc79bf617387a363ea7192acc4e1f0.camel@intel.com> (raw)
In-Reply-To: <1562875878.2840.0.camel@HansenPartnership.com>

On Thu, 2019-07-11 at 13:11 -0700, James Bottomley wrote:
> 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.

Take at look of what PSR version is supported by your panel, it likely
that a notebook shipped with Skylake will have panel that supports only
PSR1 so that patch has no effect on your machine.

sudo more /sys/kernel/debug/dri/0/i915_edp_psr_status
Sink support: yes [0x01]

Only if you have 0x03 your panel have support for PSR2.

Or check your dmesg:
[drm:intel_psr_init_dpcd [i915]] eDP panel supports PSR version 1

> 
> James
> 
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