drm/edid: MSO should only be used for non-eDP displays

As per DisplayID v2.1a spec:
If Offset 06h[2:0] is programmed to 001b (External DisplayPort), this
field shall be cleared to 00b (Not supported).

Link: https://lore.kernel.org/lkml/3abc1087618c822e5676e67a3ec2e64e506dc5ec@intel.com/
Signed-off-by: Yaroslav Bolyukin <iam@lach.pw>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

Author: CertainLach

drivers/gpu/drm/drm_displayid_internal.h

@@ -142,9 +142,13 @@ struct displayid_formula_timing_block {
 	struct displayid_formula_timings_9 timings[];
 } __packed;
 
+#define DISPLAYID_VESA_DP_TYPE		GENMASK(2, 0)
 #define DISPLAYID_VESA_MSO_OVERLAP	GENMASK(3, 0)
 #define DISPLAYID_VESA_MSO_MODE		GENMASK(6, 5)
 
+#define DISPLAYID_VESA_DP_TYPE_EDP	0
+#define DISPLAYID_VESA_DP_TYPE_DP	1
+
 struct displayid_vesa_vendor_specific_block {
 	struct displayid_block base;
 	u8 oui[3];

drivers/gpu/drm/drm_edid.c

@@ -6533,6 +6533,7 @@ static void drm_parse_vesa_specific_block(struct drm_connector *connector,
 	struct displayid_vesa_vendor_specific_block *vesa =
 		(struct displayid_vesa_vendor_specific_block *)block;
 	struct drm_display_info *info = &connector->display_info;
+	int dp_type;
 
 	if (block->num_bytes < 3) {
 		drm_dbg_kms(connector->dev,
@@ -6551,20 +6552,29 @@ static void drm_parse_vesa_specific_block(struct drm_connector *connector,
 		return;
 	}
 
-	switch (FIELD_GET(DISPLAYID_VESA_MSO_MODE, vesa->mso)) {
-	default:
-		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved MSO mode value\n",
+	dp_type = FIELD_GET(DISPLAYID_VESA_DP_TYPE, vesa->data_structure_type);
+	if (dp_type > 1) {
+		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved dp type value\n",
 			    connector->base.id, connector->name);
-		fallthrough;
-	case 0:
-		info->mso_stream_count = 0;
-		break;
-	case 1:
-		info->mso_stream_count = 2; /* 2 or 4 links */
-		break;
-	case 2:
-		info->mso_stream_count = 4; /* 4 links */
-		break;
+	}
+
+	/* MSO is only supported for eDP */
+	if (dp_type == DISPLAYID_VESA_DP_TYPE_EDP) {
+		switch (FIELD_GET(DISPLAYID_VESA_MSO_MODE, vesa->mso)) {
+		default:
+			drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved MSO mode value\n",
+				    connector->base.id, connector->name);
+			fallthrough;
+		case 0:
+			info->mso_stream_count = 0;
+			break;
+		case 1:
+			info->mso_stream_count = 2; /* 2 or 4 links */
+			break;
+		case 2:
+			info->mso_stream_count = 4; /* 4 links */
+			break;
+		}
 	}
 
 	if (info->mso_stream_count) {