drm/i915: Reinitialize HPD after runtime D3

Runtime suspends disabled all interrupts, so in order to get them back
fully we need to also do the HPD irq setup on runtime resume. Except
on VLV/CHV where the display interrupt initialization is part of the
display power well powerup.
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -1555,6 +1555,15 @@ static int intel_runtime_resume(struct device *device)
 	gen6_update_ring_freq(dev);
 
 	intel_runtime_pm_enable_interrupts(dev_priv);
+
+	/*
+	 * On VLV/CHV display interrupts are part of the display
+	 * power well, so hpd is reinitialized from there. For
+	 * everyone else do it here.
+	 */
+	if (!IS_VALLEYVIEW(dev_priv))
+		intel_hpd_init(dev_priv);
+
 	intel_enable_gt_powersave(dev);
 
 	if (ret)