drm/i915/cnl: Map VBT DDC Pin to BSpec DDC Pin.

Starting on CNL we now need to map VBT DDC Pin to
BSPec DDC Pin values. Not a direct translation anymore.

According to VBT
Block 2 (General Bytes Definition)
DDC Bus

+----------+-----------+--------------------+
| DDI Type | VBT Value | Bspec Mapped Value |
+----------+-----------+--------------------+
| DDI-B    | 0x1       | 0x1                |
| DDI-C    | 0x2       | 0x2                |
| DDI-D    | 0x3       | 0x4                |
| DDI-F    | 0x4       | 0x3                |
+----------+-----------+--------------------+

v2: Move defines to a better place.
    This is actually CNL_PCH not CNL only.
v3: Accepting Ville's suggestions: enums and array to
    to make this future proof.
v4: Protect the array access as Ville suggested.
    Also accepting all Jani's suggestions:
    	      - use already defined gmbus pin definitions.
	      - use map_ddc_pin for disambiguation.
	      - Add /* sic */ comment on inverted values
	      	so people can easily see it it nos a mistake
		we have the map 3 -> 4 and 4 -> 3 :/

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Clinton Taylor <clinton.a.taylor@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171020172641.16029-1-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/intel_bios.c

@@ -1106,6 +1106,22 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
 	}
 }
 
+static const u8 cnp_ddc_pin_map[] = {
+	[DDC_BUS_DDI_B] = GMBUS_PIN_1_BXT,
+	[DDC_BUS_DDI_C] = GMBUS_PIN_2_BXT,
+	[DDC_BUS_DDI_D] = GMBUS_PIN_4_CNP, /* sic */
+	[DDC_BUS_DDI_F] = GMBUS_PIN_3_BXT, /* sic */
+};
+
+static u8 map_ddc_pin(struct drm_i915_private *dev_priv, u8 vbt_pin)
+{
+	if (HAS_PCH_CNP(dev_priv) &&
+	    vbt_pin > 0 && vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map))
+		return cnp_ddc_pin_map[vbt_pin];
+
+	return vbt_pin;
+}
+
 static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
 			   u8 bdb_version)
 {
@@ -1191,16 +1207,7 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
 		DRM_DEBUG_KMS("Port %c is internal DP\n", port_name(port));
 
 	if (is_dvi) {
-		info->alternate_ddc_pin = ddc_pin;
-
-		/*
-		 * All VBTs that we got so far for B Stepping has this
-		 * information wrong for Port D. So, let's just ignore for now.
-		 */
-		if (IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0) &&
-		    port == PORT_D) {
-			info->alternate_ddc_pin = 0;
-		}
+		info->alternate_ddc_pin = map_ddc_pin(dev_priv, ddc_pin);
 
 		sanitize_ddc_pin(dev_priv, port);
 	}

drivers/gpu/drm/i915/intel_vbt_defs.h

@@ -306,6 +306,14 @@ struct bdb_general_features {
 
 #define LEGACY_CHILD_DEVICE_CONFIG_SIZE		33
 
+/* DDC Bus DDI Type 155+ */
+enum vbt_gmbus_ddi {
+	DDC_BUS_DDI_B = 0x1,
+	DDC_BUS_DDI_C,
+	DDC_BUS_DDI_D,
+	DDC_BUS_DDI_F,
+};
+
 /*
  * The child device config, aka the display device data structure, provides a
  * description of a port and its configuration on the platform.