drm/i915/bios: Change default clock source on PineView to use SSC

The i915 driver normally assumes the video bios has configured several
of the LVDS panel registers, and it just inherits the values. If the
vbios has not run, several of these will need to be setup.

If these are not correct then although the panel looks ok, output from an
HDMI encoder (eg, Chrontel CH7036) will be incorrect.

Signed-off-by: Mark Hayter <mdhayter@chromium.org>
[ickle: minor adjustments]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_bios.c

@@ -251,6 +251,20 @@ parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 	return;
 }
 
+static int intel_bios_ssc_frequency(struct drm_device *dev,
+				    bool alternate)
+{
+	switch (INTEL_INFO(dev)->gen) {
+	case 2:
+		return alternate ? 66 : 48;
+	case 3:
+	case 4:
+		return alternate ? 100 : 96;
+	default:
+		return alternate ? 100 : 120;
+	}
+}
+
 static void
 parse_general_features(struct drm_i915_private *dev_priv,
 		       struct bdb_header *bdb)
@@ -263,13 +277,8 @@ parse_general_features(struct drm_i915_private *dev_priv,
 		dev_priv->int_tv_support = general->int_tv_support;
 		dev_priv->int_crt_support = general->int_crt_support;
 		dev_priv->lvds_use_ssc = general->enable_ssc;
-
-		if (IS_I85X(dev))
-			dev_priv->lvds_ssc_freq = general->ssc_freq ? 66 : 48;
-		else if (IS_GEN5(dev) || IS_GEN6(dev))
-			dev_priv->lvds_ssc_freq = general->ssc_freq ? 100 : 120;
-		else
-			dev_priv->lvds_ssc_freq = general->ssc_freq ? 100 : 96;
+		dev_priv->lvds_ssc_freq =
+			intel_bios_ssc_frequency(dev, general->ssc_freq);
 	}
 }
 
@@ -553,6 +562,8 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 static void
 init_vbt_defaults(struct drm_i915_private *dev_priv)
 {
+	struct drm_device *dev = dev_priv->dev;
+
 	dev_priv->crt_ddc_pin = GMBUS_PORT_VGADDC;
 
 	/* LFP panel data */
@@ -565,7 +576,11 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 	/* general features */
 	dev_priv->int_tv_support = 1;
 	dev_priv->int_crt_support = 1;
-	dev_priv->lvds_use_ssc = 0;
+
+	/* Default to using SSC */
+	dev_priv->lvds_use_ssc = 1;
+	dev_priv->lvds_ssc_freq = intel_bios_ssc_frequency(dev, 1);
+	DRM_DEBUG("Set default to SSC at %dMHz\n", dev_priv->lvds_ssc_freq);
 
 	/* eDP data */
 	dev_priv->edp.bpp = 18;