Revert "drm/i915/ilk: Don't disable SSC source if it's in use"

This reverts commit bcb66592.
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

drivers/gpu/drm/i915/intel_display.c

@@ -6526,14 +6526,12 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_encoder *encoder;
-	int i;
 	u32 val, final;
 	bool has_lvds = false;
 	bool has_cpu_edp = false;
 	bool has_panel = false;
 	bool has_ck505 = false;
 	bool can_ssc = false;
-	bool using_ssc_source = false;
 
 	/* We need to take the global config into account */
 	for_each_intel_encoder(dev, encoder) {
@@ -6558,22 +6556,8 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
 		can_ssc = true;
 	}
 
-	/* Check if any DPLLs are using the SSC source */
-	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
-		u32 temp = I915_READ(PCH_DPLL(i));
-
-		if (!(temp & DPLL_VCO_ENABLE))
-			continue;
-
-		if ((temp & PLL_REF_INPUT_MASK) ==
-		    PLLB_REF_INPUT_SPREADSPECTRUMIN) {
-			using_ssc_source = true;
-			break;
-		}
-	}
-
-	DRM_DEBUG_KMS("has_panel %d has_lvds %d has_ck505 %d using_ssc_source %d\n",
-		      has_panel, has_lvds, has_ck505, using_ssc_source);
+	DRM_DEBUG_KMS("has_panel %d has_lvds %d has_ck505 %d\n",
+		      has_panel, has_lvds, has_ck505);
 
 	/* Ironlake: try to setup display ref clock before DPLL
 	 * enabling. This is only under driver's control after
@@ -6610,9 +6594,9 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
 				final |= DREF_CPU_SOURCE_OUTPUT_NONSPREAD;
 		} else
 			final |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
-	} else if (using_ssc_source) {
-		final |= DREF_SSC_SOURCE_ENABLE;
-		final |= DREF_SSC1_ENABLE;
+	} else {
+		final |= DREF_SSC_SOURCE_DISABLE;
+		final |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
 	}
 
 	if (final == val)
@@ -6658,7 +6642,7 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
 		POSTING_READ(PCH_DREF_CONTROL);
 		udelay(200);
 	} else {
-		DRM_DEBUG_KMS("Disabling CPU source output\n");
+		DRM_DEBUG_KMS("Disabling SSC entirely\n");
 
 		val &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
 
@@ -6669,20 +6653,16 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
 		POSTING_READ(PCH_DREF_CONTROL);
 		udelay(200);
 
-		if (!using_ssc_source) {
-			DRM_DEBUG_KMS("Disabling SSC source\n");
-
-			/* Turn off the SSC source */
-			val &= ~DREF_SSC_SOURCE_MASK;
-			val |= DREF_SSC_SOURCE_DISABLE;
+		/* Turn off the SSC source */
+		val &= ~DREF_SSC_SOURCE_MASK;
+		val |= DREF_SSC_SOURCE_DISABLE;
 
-			/* Turn off SSC1 */
-			val &= ~DREF_SSC1_ENABLE;
+		/* Turn off SSC1 */
+		val &= ~DREF_SSC1_ENABLE;
 
-			I915_WRITE(PCH_DREF_CONTROL, val);
-			POSTING_READ(PCH_DREF_CONTROL);
-			udelay(200);
-		}
+		I915_WRITE(PCH_DREF_CONTROL, val);
+		POSTING_READ(PCH_DREF_CONTROL);
+		udelay(200);
 	}
 
 	BUG_ON(val != final);