drm/i915: clean up VBT eDP link param decoding

Use defines, do not set anything if VBT has values unknown to us.
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_bios.c

@@ -560,47 +560,71 @@ parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
 
 	dev_priv->vbt.edp_pps = *edp_pps;
 
-	dev_priv->vbt.edp_rate = edp_link_params->rate ? DP_LINK_BW_2_7 :
-		DP_LINK_BW_1_62;
+	switch (edp_link_params->rate) {
+	case EDP_RATE_1_62:
+		dev_priv->vbt.edp_rate = DP_LINK_BW_1_62;
+		break;
+	case EDP_RATE_2_7:
+		dev_priv->vbt.edp_rate = DP_LINK_BW_2_7;
+		break;
+	default:
+		DRM_DEBUG_KMS("VBT has unknown eDP link rate value %u\n",
+			      edp_link_params->rate);
+		break;
+	}
+
 	switch (edp_link_params->lanes) {
-	case 0:
+	case EDP_LANE_1:
 		dev_priv->vbt.edp_lanes = 1;
 		break;
-	case 1:
+	case EDP_LANE_2:
 		dev_priv->vbt.edp_lanes = 2;
 		break;
-	case 3:
-	default:
+	case EDP_LANE_4:
 		dev_priv->vbt.edp_lanes = 4;
 		break;
+	default:
+		DRM_DEBUG_KMS("VBT has unknown eDP lane count value %u\n",
+			      edp_link_params->lanes);
+		break;
 	}
+
 	switch (edp_link_params->preemphasis) {
-	case 0:
+	case EDP_PREEMPHASIS_NONE:
 		dev_priv->vbt.edp_preemphasis = DP_TRAIN_PRE_EMPHASIS_0;
 		break;
-	case 1:
+	case EDP_PREEMPHASIS_3_5dB:
 		dev_priv->vbt.edp_preemphasis = DP_TRAIN_PRE_EMPHASIS_3_5;
 		break;
-	case 2:
+	case EDP_PREEMPHASIS_6dB:
 		dev_priv->vbt.edp_preemphasis = DP_TRAIN_PRE_EMPHASIS_6;
 		break;
-	case 3:
+	case EDP_PREEMPHASIS_9_5dB:
 		dev_priv->vbt.edp_preemphasis = DP_TRAIN_PRE_EMPHASIS_9_5;
 		break;
+	default:
+		DRM_DEBUG_KMS("VBT has unknown eDP pre-emphasis value %u\n",
+			      edp_link_params->preemphasis);
+		break;
 	}
+
 	switch (edp_link_params->vswing) {
-	case 0:
+	case EDP_VSWING_0_4V:
 		dev_priv->vbt.edp_vswing = DP_TRAIN_VOLTAGE_SWING_400;
 		break;
-	case 1:
+	case EDP_VSWING_0_6V:
 		dev_priv->vbt.edp_vswing = DP_TRAIN_VOLTAGE_SWING_600;
 		break;
-	case 2:
+	case EDP_VSWING_0_8V:
 		dev_priv->vbt.edp_vswing = DP_TRAIN_VOLTAGE_SWING_800;
 		break;
-	case 3:
+	case EDP_VSWING_1_2V:
 		dev_priv->vbt.edp_vswing = DP_TRAIN_VOLTAGE_SWING_1200;
 		break;
+	default:
+		DRM_DEBUG_KMS("VBT has unknown eDP voltage swing value %u\n",
+			      edp_link_params->vswing);
+		break;
 	}
 }