On Fri, Nov 22, 2013 at 12:46:40PM -0800, Jesse Barnes wrote:
> On Fri, 22 Nov 2013 20:35:24 +0000
> Chris Wilson <ch...@chris-wilson.co.uk> wrote:
>
> > I believe, and an evening of i-g-t, that our original workaround for the
> > missed interrupts on Sandybridge, that of holding forcewake whilst we
> > wait for an interrupts, is no longer required. This leaves us dependent
> > on the second workaround of forcing an UC read of the ACTHD before
> > reading back the seqno from the snooped HWS. Dropping the forcewake
> > should allow us to conserve a little power, not much as the GPU is meant
> > to be busy whilst we wait for it!
> >
> > Cc: Jesse Barnes <jbar...@virtuousgeek.org>
> > Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> > ---
> > drivers/gpu/drm/i915/intel_ringbuffer.c | 7 -------
> > 1 file changed, 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > index 80893af4062b..6b121ba9d3f7 100644
> > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > @@ -1030,11 +1030,6 @@ gen6_ring_get_irq(struct intel_ring_buffer *ring)
> > if (!dev->irq_enabled)
> > return false;
> >
> > - /* It looks like we need to prevent the gt from suspending while waiting
> > - * for an notifiy irq, otherwise irqs seem to get lost on at least the
> > - * blt/bsd rings on ivb. */
> > - gen6_gt_force_wake_get(dev_priv);
> > -
> > spin_lock_irqsave(&dev_priv->irq_lock, flags);
> > if (ring->irq_refcount++ == 0) {
> > if (HAS_L3_DPF(dev) && ring->id == RCS)
> > @@ -1066,8 +1061,6 @@ gen6_ring_put_irq(struct intel_ring_buffer *ring)
> > ilk_disable_gt_irq(dev_priv, ring->irq_enable_mask);
> > }
> > spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
> > -
> > - gen6_gt_force_wake_put(dev_priv);
> > }
> >
> > static bool
>
> Yay! This is just what I was testing on BYT today, and it works there
> too (and gives me tons more RC6 residency).
Risky imo, since I see missed interrupts sporadically on all my gen6+
machines, and we don't have any solid testcase in igt that readily hits
them. Expect a swift strike with the revert hammer if this causes trouble
;-)
> Reviewed-by: Jesse Barnes <jbar...@virtuousgeek.org>
Queued for -next, thanks for the patch.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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