From 0a92d4f634f93efe71b87e21222a37fbd4def66a Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Thu, 19 Sep 2013 17:03:05 -0300
Subject: drm/i915: POSTING_READ IPS_CTL before waiting for the vblank

Make sure we write to IPS before we actually wait.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 81c12f6e78c535533e9258bd9476b5d7419d3cce)
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a45ff17af834..5d0b03fbdac7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3386,6 +3386,7 @@ static void hsw_disable_ips(struct intel_crtc *crtc)
 
 	assert_plane_enabled(dev_priv, crtc->plane);
 	I915_WRITE(IPS_CTL, 0);
+	POSTING_READ(IPS_CTL);
 
 	/* We need to wait for a vblank before we can disable the plane. */
 	intel_wait_for_vblank(dev, crtc->pipe);
-- 
1.8.5.rc3