drm/i915/edp: always add fixed mode to probed modes in ->get_modes()

Unconditionally add fixed mode to probed modes even if EDID is present
and has modes. Prepare for cases where the fixed mode is not present in
EDID (such as eDP MSO).

Cc: Nischal Varide <nischal.varide@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6979f123f3e4ed948333f1b181202bbced3c3e85.1613054234.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_dp.c

@@ -5547,19 +5547,18 @@ static int intel_dp_get_modes(struct drm_connector *connector)
 {
 	struct intel_connector *intel_connector = to_intel_connector(connector);
 	struct edid *edid;
+	int num_modes = 0;
 
 	edid = intel_connector->detect_edid;
 	if (edid) {
-		int ret = intel_connector_update_modes(connector, edid);
+		num_modes = intel_connector_update_modes(connector, edid);
 
 		if (intel_vrr_is_capable(connector))
 			drm_connector_set_vrr_capable_property(connector,
 							       true);
-		if (ret)
-			return ret;
 	}
 
-	/* if eDP has no EDID, fall back to fixed mode */
+	/* Also add fixed mode, which may or may not be present in EDID */
 	if (intel_dp_is_edp(intel_attached_dp(intel_connector)) &&
 	    intel_connector->panel.fixed_mode) {
 		struct drm_display_mode *mode;
@@ -5568,10 +5567,13 @@ static int intel_dp_get_modes(struct drm_connector *connector)
 					  intel_connector->panel.fixed_mode);
 		if (mode) {
 			drm_mode_probed_add(connector, mode);
-			return 1;
+			num_modes++;
 		}
 	}
 
+	if (num_modes)
+		return num_modes;
+
 	if (!edid) {
 		struct intel_dp *intel_dp = intel_attached_dp(intel_connector);
 		struct drm_display_mode *mode;
@@ -5581,11 +5583,11 @@ static int intel_dp_get_modes(struct drm_connector *connector)
 					      intel_dp->downstream_ports);
 		if (mode) {
 			drm_mode_probed_add(connector, mode);
-			return 1;
+			num_modes++;
 		}
 	}
 
-	return 0;
+	return num_modes;
 }
 
 static int