Re: Intel i915 freeze on latest git

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue, 01 Feb 2011 16:57:37 +0000
Chris Wilson <chris@chris-wilson.co.uk> wrote:

> On Tue, 1 Feb 2011 08:31:12 -0800, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > The bisect is interesting, I'd have expected a failure when we
> > re-enabled rc6 on ILK or when we fixed up the ring buffer init.
> 
> Yes, that was my instinct as well.
> 
> Though that patch does do have one subtlety:
> 
> ironlake_enable_rc6():
> +      I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) & ~RCX_SW_EXIT);
> 
> So it appears the patch may in fact be enabling render standby, when it
> was actually dropped in
> 
> commit 88271da3f3da75d6eaef5e768c82a1627edf7088
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Wed Jan 5 12:01:24 2011 -0800
> 
>     drm/i915: re-enable rc6 support for Ironlake+
> 
> intel_enable_clock_gating():
> -	I915_WRITE(MCHBAR_RENDER_STANDBY,
> -	           I915_READ(MCHBAR_RENDER_STANDBY) & ~RCX_SW_EXIT);
> 
> 
> So, if this is the issue, then simply commenting out the tweaking of
> RSTDBYCTL in ironlake_enable_rc6() should prevent the hang.

IIRC that really was a cleanup, clearing RCX_SW_EXIT on my machine was
unnecessary, since it was already clear.  But it's worth trying
anyway...

-- 
Jesse Barnes, Intel Open Source Technology Center