From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Meyer <thomas@m3y3r.de>
Subject: Re: Linux 3.16-rc2
Date: Tue, 24 Jun 2014 14:24:30 +0200
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To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, Linus Torvalds <torvalds@linux-foundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Am Dienstag, den 24.06.2014, 12:57 +0100 schrieb Chris Wilson:
> On Tue, Jun 24, 2014 at 02:06:24PM +0300, Jani Nikula wrote:
> > On Tue, 24 Jun 2014, Thomas Meyer <thomas@m3y3r.de> wrote:
> > > the i915 driver is still broken in 3.16-rc2. Resume from ram crashes the
> > > X server.
> > 
> > This is not new to 3.16-rc2; apparently we've had it since v3.15-rc4
> > [1]. Also related [2].
> > 
> > Chris, any fresh ideas?
> 
> Nope. The bug is https://bugs.freedesktop.org/show_bug.cgi?id=76554
> everything we know and have tried is there. Which is not much more than
> at time of the original incarnation:
> 
> commit 50aa253d820ad4577e2231202f2c8fd89f9dc4e6
> Author: Keith Packard <keithp@keithp.com>
> Date:   Tue Oct 14 17:20:35 2008 -0700
> 
>     i915: Fix up ring initialization to cover G45 oddities
>     
>     G45 appears quite sensitive to ring initialization register writes,
>     sometimes leaving the HEAD register with the START register contents. Check
>     to make sure HEAD is reset correctly when START is written, and fix it up,
>     screaming loudly.
> -Chris
> 

Hi,

so why not revert 78f2975eec9faff353a6194e854d3d39907bab68 (drm/i915:
Move all ring resets before setting the HWS page) ?

Without this commit 3.15 is super stable for me. This seems to be also
true for others according to above bug report.

thomas