Update the hardware breadcrumb in the sarea on irq reception so that

clients can avoid an ioctl waiting on fences that have already been
    received. Would be even better if the hardware did the update itself.

shared-core/i915_irq.c

@@ -54,6 +54,8 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS)
 
 	I915_WRITE16(I915REG_INT_IDENTITY_R, temp);
 
+	dev_priv->sarea_priv->last_dispatch = READ_BREADCRUMB(dev_priv);
+
 	if (temp & USER_INT_FLAG)
 		DRM_WAKEUP(&dev_priv->irq_queue);