linux-kernel - Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window

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Date:	Tue, 21 Jun 2016 09:53:15 -0400
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Jani Nikula <jani.nikula@...ux.intel.com>,
	Daniel Vetter <daniel@...ll.ch>
Cc:	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	"Syrjala, Ville" <ville.syrjala@...el.com>
Subject: Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7
 merge window

On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote:
> Cc: Ville
> 
> On Mon, 20 Jun 2016, James Bottomley <
> James.Bottomley@...senPartnership.com> wrote:
> > OK, my candidate bad commit is this one:
> > 
> > commit a05628195a0d9f3173dd9aa76f482aef692e46ee
> > Author: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > Date:   Mon Apr 11 10:23:51 2016 +0300
> > 
> >     drm/i915: Get panel_type from OpRegion panel details
> > 
> > After being more careful about waiting to identify flicker, this 
> > one seems to be the one the bisect finds.  I'm now running v4.7-rc3
> > with this one reverted and am currently seeing no flicker problems.
> >   It is, however, early days because the flicker can hide for long 
> > periods, so I 'll wait until Monday evening and a few reboots 
> > before declaring victory.
> 
> If that turns out to be the bad commit, it doesn't really surprise 
> me, and that in itself is depressing.

As far as I can tell, after running for a day with this reverted, this
is the problem.  The flicker hasn't appeared with it reverted.  It's
pretty noticeable with this commit included.

> It might be helpful if you could add drm.debug=14 module parameter, 
> and provide dmesgs from boot both with and without the above commit 
> (it's enough to see i915 load). Please also provide /sys/kernel/debug
> /dri/0/i915_opregion.

Assuming the Mailing list doesn't eat the attachments, they should all
be included.

James


View attachment "dmesg.bad.txt" of type "text/plain" (121693 bytes)

View attachment "dmesg.good.txt" of type "text/plain" (121249 bytes)

Download attachment "i915_opregion.bad" of type "application/octet-stream" (8192 bytes)

Download attachment "i915_opregion.good" of type "application/octet-stream" (8192 bytes)