[Intel-gfx] [PATCH] drm/i915: fix up gt init sequence fallout

[Daniel Vetter]

On Sun, Jul 21, 2013 at 12:50:03PM +0100, Chris Wilson wrote:
> On Sun, Jul 21, 2013 at 01:16:24PM +0200, Daniel Vetter wrote:
> > The regression fix for gen6+ rps fallout
> > 
> > commit 7dcd2677ea912573d9ed4bcd629b0023b2d11505
> > Author: Konstantin Khlebnikov <khlebnikov at openvz.org>
> > Date:   Wed Jul 17 10:22:58 2013 +0400
> > 
> >     drm/i915: fix long-standing SNB regression in power consumption after resume
> > 
> > unintentionally also changed the init sequence ordering between
> > gt_init and gt_reset - we need to reset BIOS damage like leftover
> > forcewake references before we run our own code. Otherwise we can get
> > nasty dmesg noise like
> > 
> > [drm:__gen6_gt_force_wake_mt_get] *ERROR* Timed out waiting for forcewake old ack to clear.
> > 
> > again. Since _reset suggests that we first need to have stuff
> > initialized (which isn't the case here) call it sanitze instead.
> > 
> > While at it also block out the rps disable introduce by the above
> > commit on ilk: We don't have any knowledge of ilk rps being broken in
> > similar ways. And the disable functions uses the default hw state
> > which is only read out when we're enabling rps. So essentially we've
> > been writing random grabage into that register.
> > 
> > Reported-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Konstantin Khlebnikov <khlebnikov at openvz.org>
> > Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
> > Cc: stable at vger.kernel.org
> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> Indeed, on ilk this does look a bit fishy.
> 
> Tested-by: Chris Wilson <chris at chris-wilson.co.uk>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Merged to -fixes, thanks for digging this out and testing&reviewing my
patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch