diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 27805a9ca877feadb743c57039e1cef084df5520..c7aa29bfdea995e7120a67903a56d5489a5ece95 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -883,6 +883,7 @@ static void ironlake_edp_pll_off(struct drm_encoder *encoder)
 	dpa_ctl = I915_READ(DP_A);
 	dpa_ctl |= DP_PLL_ENABLE;
 	I915_WRITE(DP_A, dpa_ctl);
+	POSTING_READ(DP_A);
 	udelay(200);
 }