diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 603949622104d36dd8e266c839479f5a3fae60f6..f9999357716861e2e8625ea6d91de545a31ae3a7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5113,31 +5113,32 @@ static void ironlake_update_pch_refclk(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_mode_config *mode_config = &dev->mode_config;
-	struct drm_crtc *crtc;
 	struct intel_encoder *encoder;
-	struct intel_encoder *has_edp_encoder = NULL;
 	u32 temp;
 	bool has_lvds = false;
+	bool has_cpu_edp = false;
+	bool has_pch_edp = false;
+	bool has_panel = false;
 
 	/* We need to take the global config into account */
-	list_for_each_entry(crtc, &mode_config->crtc_list, head) {
-		if (!crtc->enabled)
-			continue;
-
-		list_for_each_entry(encoder, &mode_config->encoder_list,
-				    base.head) {
-			if (encoder->base.crtc != crtc)
-				continue;
-
-			switch (encoder->type) {
-			case INTEL_OUTPUT_LVDS:
-				has_lvds = true;
-			case INTEL_OUTPUT_EDP:
-				has_edp_encoder = encoder;
-				break;
-			}
+	list_for_each_entry(encoder, &mode_config->encoder_list,
+			    base.head) {
+		switch (encoder->type) {
+		case INTEL_OUTPUT_LVDS:
+			has_panel = true;
+			has_lvds = true;
+			break;
+		case INTEL_OUTPUT_EDP:
+			has_panel = true;
+			if (intel_encoder_is_pch_edp(&encoder->base))
+				has_pch_edp = true;
+			else
+				has_cpu_edp = true;
+			break;
 		}
 	}
+	DRM_DEBUG_KMS("has_panel %d has_lvds %d has_pch_edp %d has_cpu_edp %d\n",
+		      has_panel, has_lvds, has_pch_edp, has_cpu_edp);
 
 	/* Ironlake: try to setup display ref clock before DPLL
 	 * enabling. This is only under driver's control after
@@ -5148,36 +5149,57 @@ static void ironlake_update_pch_refclk(struct drm_device *dev)
 	/* Always enable nonspread source */
 	temp &= ~DREF_NONSPREAD_SOURCE_MASK;
 	temp |= DREF_NONSPREAD_SOURCE_ENABLE;
-	temp &= ~DREF_SSC_SOURCE_MASK;
-	temp |= DREF_SSC_SOURCE_ENABLE;
-	I915_WRITE(PCH_DREF_CONTROL, temp);
 
-	POSTING_READ(PCH_DREF_CONTROL);
-	udelay(200);
+	if (has_panel) {
+		temp &= ~DREF_SSC_SOURCE_MASK;
+		temp |= DREF_SSC_SOURCE_ENABLE;
 
-	if (has_edp_encoder) {
+		/* SSC must be turned on before enabling the CPU output  */
 		if (intel_panel_use_ssc(dev_priv)) {
+			DRM_DEBUG_KMS("Using SSC on panel\n");
 			temp |= DREF_SSC1_ENABLE;
-			I915_WRITE(PCH_DREF_CONTROL, temp);
-
-			POSTING_READ(PCH_DREF_CONTROL);
-			udelay(200);
 		}
+
+		/* Get SSC going before enabling the outputs */
+		I915_WRITE(PCH_DREF_CONTROL, temp);
+		POSTING_READ(PCH_DREF_CONTROL);
+		udelay(200);
+
 		temp &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
 
 		/* Enable CPU source on CPU attached eDP */
-		if (!intel_encoder_is_pch_edp(&has_edp_encoder->base)) {
-			if (intel_panel_use_ssc(dev_priv))
+		if (has_cpu_edp) {
+			if (intel_panel_use_ssc(dev_priv)) {
+				DRM_DEBUG_KMS("Using SSC on eDP\n");
 				temp |= DREF_CPU_SOURCE_OUTPUT_DOWNSPREAD;
+			}
 			else
 				temp |= DREF_CPU_SOURCE_OUTPUT_NONSPREAD;
-		} else {
-			/* Enable SSC on PCH eDP if needed */
-			if (intel_panel_use_ssc(dev_priv)) {
-				DRM_ERROR("enabling SSC on PCH\n");
-				temp |= DREF_SUPERSPREAD_SOURCE_ENABLE;
-			}
-		}
+		} else
+			temp |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
+
+		I915_WRITE(PCH_DREF_CONTROL, temp);
+		POSTING_READ(PCH_DREF_CONTROL);
+		udelay(200);
+	} else {
+		DRM_DEBUG_KMS("Disabling SSC entirely\n");
+
+		temp &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
+
+		/* Turn off CPU output */
+		temp |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
+
+		I915_WRITE(PCH_DREF_CONTROL, temp);
+		POSTING_READ(PCH_DREF_CONTROL);
+		udelay(200);
+
+		/* Turn off the SSC source */
+		temp &= ~DREF_SSC_SOURCE_MASK;
+		temp |= DREF_SSC_SOURCE_DISABLE;
+
+		/* Turn off SSC1 */
+		temp &= ~ DREF_SSC1_ENABLE;
+
 		I915_WRITE(PCH_DREF_CONTROL, temp);
 		POSTING_READ(PCH_DREF_CONTROL);
 		udelay(200);