drm/i915: split refclk code out of ironlake_crtc_mode_set

Just a cleanup to make the mode_set function more manageable.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Tested-By: NEugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-By: NEugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_display.c

@@ -5241,6 +5241,40 @@ void ironlake_init_pch_refclk(struct drm_device *dev)
 	}
 }
 
+static int ironlake_get_refclk(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_encoder *encoder;
+	struct drm_mode_config *mode_config = &dev->mode_config;
+	struct intel_encoder *edp_encoder = NULL;
+	int num_connectors = 0;
+	bool is_lvds = false;
+
+	list_for_each_entry(encoder, &mode_config->encoder_list, base.head) {
+		if (encoder->base.crtc != crtc)
+			continue;
+
+		switch (encoder->type) {
+		case INTEL_OUTPUT_LVDS:
+			is_lvds = true;
+			break;
+		case INTEL_OUTPUT_EDP:
+			edp_encoder = encoder;
+			break;
+		}
+		num_connectors++;
+	}
+
+	if (is_lvds && intel_panel_use_ssc(dev_priv) && num_connectors < 2) {
+		DRM_DEBUG_KMS("using SSC reference clock of %d MHz\n",
+			      dev_priv->lvds_ssc_freq);
+		return dev_priv->lvds_ssc_freq * 1000;
+	}
+
+	return 120000;
+}
+
 static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 				  struct drm_display_mode *mode,
 				  struct drm_display_mode *adjusted_mode,
@@ -5300,10 +5334,7 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		num_connectors++;
 	}
 
-	/*
-	 * Every reference clock in a PCH system is 120MHz
-	 */
-	refclk = 120000;
+	refclk = ironlake_get_refclk(crtc);
 
 	/*
 	 * Returns a set of divisors for the desired target clock with the given