diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 601ffc2..81cca48 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1108,14 +1108,23 @@ void intel_ddi_disable_pipe_clock(struct intel_crtc *intel_crtc)
 
 void intel_ddi_pre_enable(struct intel_encoder *intel_encoder)
 {
-	struct drm_crtc *crtc = intel_encoder->base.crtc;
-	struct drm_i915_private *dev_priv = crtc->dev->dev_private;
+	struct drm_encoder *encoder = &intel_encoder->base;
+	struct drm_crtc *crtc = encoder->crtc;
+	struct drm_i915_private *dev_priv = encoder->dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	enum port port = intel_ddi_get_encoder_port(intel_encoder);
 
 	WARN_ON(intel_crtc->ddi_pll_sel == PORT_CLK_SEL_NONE);
 
 	I915_WRITE(PORT_CLK_SEL(port), intel_crtc->ddi_pll_sel);
+
+	if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT) {
+		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+
+		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
+		intel_dp_start_link_train(intel_dp);
+		intel_dp_complete_link_train(intel_dp);
+	}
 }
 
 static void intel_wait_ddi_buf_idle(struct drm_i915_private *dev_priv,
@@ -1210,3 +1219,43 @@ void intel_ddi_pll_init(struct drm_device *dev)
 	if (val & LCPLL_PLL_DISABLE)
 		DRM_ERROR("LCPLL is disabled\n");
 }
+
+void intel_ddi_prepare_link_retrain(struct drm_encoder *encoder)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	struct drm_i915_private *dev_priv = encoder->dev->dev_private;
+	enum port port = intel_dp->port;
+	bool wait;
+	uint32_t val;
+
+	if (I915_READ(DP_TP_CTL(port)) & DP_TP_CTL_ENABLE) {
+		val = I915_READ(DDI_BUF_CTL(port));
+		if (val & DDI_BUF_CTL_ENABLE) {
+			val &= ~DDI_BUF_CTL_ENABLE;
+			I915_WRITE(DDI_BUF_CTL(port), val);
+			wait = true;
+		}
+
+		val = I915_READ(DP_TP_CTL(port));
+		val &= ~(DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_MASK);
+		val |= DP_TP_CTL_LINK_TRAIN_PAT1;
+		I915_WRITE(DP_TP_CTL(port), val);
+		POSTING_READ(DP_TP_CTL(port));
+
+		if (wait)
+			intel_wait_ddi_buf_idle(dev_priv, port);
+	}
+
+	val = DP_TP_CTL_ENABLE | DP_TP_CTL_MODE_SST |
+	      DP_TP_CTL_LINK_TRAIN_PAT1 | DP_TP_CTL_SCRAMBLE_DISABLE;
+	if (intel_dp->link_configuration[1] & DP_LANE_COUNT_ENHANCED_FRAME_EN)
+		val |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
+	I915_WRITE(DP_TP_CTL(port), val);
+	POSTING_READ(DP_TP_CTL(port));
+
+	intel_dp->DP |= DDI_BUF_CTL_ENABLE;
+	I915_WRITE(DDI_BUF_CTL(port), intel_dp->DP);
+	POSTING_READ(DDI_BUF_CTL(port));
+
+	udelay(600);
+}
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3a5fe2f..36687d9 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -102,8 +102,6 @@ bool intel_encoder_is_pch_edp(struct drm_encoder *encoder)
 	return is_pch_edp(intel_dp);
 }
 
-static void intel_dp_start_link_train(struct intel_dp *intel_dp);
-static void intel_dp_complete_link_train(struct intel_dp *intel_dp);
 static void intel_dp_link_down(struct intel_dp *intel_dp);
 
 void
@@ -1266,7 +1264,7 @@ static void ironlake_edp_pll_off(struct intel_dp *intel_dp)
 }
 
 /* If the sink supports it, try to set the power state appropriately */
-static void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
+void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
 {
 	int ret, i;
 
@@ -1854,16 +1852,20 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
 }
 
 /* Enable corresponding port and start training pattern 1 */
-static void
+void
 intel_dp_start_link_train(struct intel_dp *intel_dp)
 {
-	struct drm_device *dev = intel_dp->base.base.dev;
+	struct drm_encoder *encoder = &intel_dp->base.base;
+	struct drm_device *dev = encoder->dev;
 	int i;
 	uint8_t voltage;
 	bool clock_recovery = false;
 	int voltage_tries, loop_tries;
 	uint32_t DP = intel_dp->DP;
 
+	if (IS_HASWELL(dev))
+		intel_ddi_prepare_link_retrain(encoder);
+
 	/* Write the link configuration data */
 	intel_dp_aux_native_write(intel_dp, DP_LINK_BW_SET,
 				  intel_dp->link_configuration,
@@ -1949,7 +1951,7 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
 	intel_dp->DP = DP;
 }
 
-static void
+void
 intel_dp_complete_link_train(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp->base.base.dev;
@@ -2035,6 +2037,24 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t DP = intel_dp->DP;
 
+	/*
+	 * DDI code has a strict mode set sequence and we should try to respect
+	 * it, otherwise we might hang the machine in many different ways. So we
+	 * really should be disabling the port only on a complete crtc_disable
+	 * sequence. This function is just called under two conditions on DDI
+	 * code:
+	 * - Link train failed while doing crtc_enable, and on this case we
+	 *   really should respect the mode set sequence and wait for a
+	 *   crtc_disable.
+	 * - Someone turned the monitor off and intel_dp_check_link_status
+	 *   called us. We don't need to disable the whole port on this case, so
+	 *   when someone turns the monitor on again,
+	 *   intel_ddi_prepare_link_retrain will take care of redoing the link
+	 *   train.
+	 */
+	if (IS_HASWELL(dev))
+		return;
+
 	if (WARN_ON((I915_READ(intel_dp->output_reg) & DP_PORT_EN) == 0))
 		return;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index d89d428..95cbd67 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -423,6 +423,9 @@ void
 intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
 		 struct drm_display_mode *adjusted_mode);
 extern void intel_dp_init_link_config(struct intel_dp *intel_dp);
+extern void intel_dp_start_link_train(struct intel_dp *intel_dp);
+extern void intel_dp_complete_link_train(struct intel_dp *intel_dp);
+extern void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
 extern bool intel_dpd_is_edp(struct drm_device *dev);
 extern void intel_edp_link_config(struct intel_encoder *, int *, int *);
 extern int intel_edp_target_clock(struct intel_encoder *,
@@ -599,5 +602,6 @@ extern void intel_ddi_pre_enable(struct intel_encoder *intel_encoder);
 extern void intel_ddi_post_disable(struct intel_encoder *intel_encoder);
 extern void intel_ddi_put_crtc_pll(struct drm_crtc *crtc);
 extern void intel_ddi_set_pipe_settings(struct drm_crtc *crtc);
+extern void intel_ddi_prepare_link_retrain(struct drm_encoder *encoder);
 
 #endif /* __INTEL_DRV_H__ */
