[Intel-gfx] [PATCH] drm/i915: hold forcewake around ring hw init

[Daniel Vetter]

On Mon, Jun 04, 2012 at 09:47:54AM -0300, Eugeni Dodonov wrote:
> On 06/04/2012 06:18 AM, Daniel Vetter wrote:
> >Empirical evidence suggests that we need to: On at least one ivb
> >machine when running the hangman i-g-t test, the rings don't properly
> >initialize properly - the RING_START registers seems to be stuck at
> >all zeros.
> >
> >Holding forcewake around this register init sequences makes chip reset
> >reliable again. Note that this is not the first such issue:
> >
> >commit f01db988ef6f6c70a6cc36ee71e4a98a68901229
> >Author: Sean Paul<seanpaul at chromium.org>
> >Date:   Fri Mar 16 12:43:22 2012 -0400
> >
> >     drm/i915: Add wait_for in init_ring_common
> >
> >added delay loops to make RING_START and RING_CTL initialization
> >reliable on the blt ring at boot-up. So I guess it won't hurt if we do
> >this unconditionally for all force_wake needing gpus.
> >
> >To avoid copy&pasting of the HAS_FORCE_WAKE check I've added a new
> >intel_info bit for that.
> >
> >v2: Fixup missing commas in static struct and properly handling the
> >error case in init_ring_common, both noticed by Jani Nikula.
> >
> >Cc: stable at vger.kernel.org
> >Reported-by: Yang Guang<guang.a.yang at intel.com>
> >Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50522
> >Signed-Off-by: Daniel Vetter<daniel.vetter at ffwll.ch>
> 
> The new .has_forcewake looks nice! Just one very tiny bikeshed below :).
> 
> Reviewed-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
Picked up for -fixes, thanks for the review.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
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