drm/i915: Set AGPBUSY# bit in init_clock_gating

I don't see why we wouldn't want interrupts to wake up the CPU from C3
always, so just set the AGPBUSY# bit in gen3_init_clock_gating().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -2628,10 +2628,6 @@ static int i915_enable_vblank(struct drm_device *dev, int pipe)
 	else
 		i915_enable_pipestat(dev_priv, pipe,
 				     PIPE_VBLANK_INTERRUPT_STATUS);
-
-	/* maintain vblank delivery even in deep C-states */
-	if (INTEL_INFO(dev)->gen == 3)
-		I915_WRITE(INSTPM, _MASKED_BIT_DISABLE(INSTPM_AGPBUSY_DIS));
 	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 	return 0;
@@ -2695,9 +2691,6 @@ static void i915_disable_vblank(struct drm_device *dev, int pipe)
 	unsigned long irqflags;
 
 	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
-	if (INTEL_INFO(dev)->gen == 3)
-		I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_AGPBUSY_DIS));
-
 	i915_disable_pipestat(dev_priv, pipe,
 			      PIPE_VBLANK_INTERRUPT_STATUS |
 			      PIPE_START_VBLANK_INTERRUPT_STATUS);

drivers/gpu/drm/i915/intel_pm.c

@@ -5504,6 +5504,9 @@ static void gen3_init_clock_gating(struct drm_device *dev)
 
 	/* IIR "flip pending" means done if this bit is set */
 	I915_WRITE(ECOSKPD, _MASKED_BIT_DISABLE(ECO_FLIP_DONE));
+
+	/* interrupts should cause a wake up from C3 */
+	I915_WRITE(INSTPM, _MASKED_BIT_DISABLE(INSTPM_AGPBUSY_DIS));
 }
 
 static void i85x_init_clock_gating(struct drm_device *dev)