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

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Date:	Mon, 20 Jun 2016 11:03:44 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	James Bottomley <James.Bottomley@...senPartnership.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


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.

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.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Technology Center