Re: [Intel-gfx] Linux 3.16-rc2

[Chris Wilson]

On Tue, Jun 24, 2014 at 02:24:30PM +0200, Thomas Meyer wrote:
> 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@xxxxxxxx> 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@xxxxxxxxxx>
> > 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) ?

Because that patch was in response to a boot time regression.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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