diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index 5923bbc232be..11aff485d8fa 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -1331,6 +1331,7 @@ static ssize_t i915_joiner_write(struct file *file,
 {
 	struct seq_file *m = file->private_data;
 	struct intel_connector *connector = m->private;
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	int force_joined_pipes = 0;
 	int ret;
 
@@ -1347,6 +1348,13 @@ static ssize_t i915_joiner_write(struct file *file,
 	case 2:
 		connector->force_joined_pipes = force_joined_pipes;
 		break;
+	case 4:
+		if (HAS_ULTRAJOINER(i915)) {
+			connector->force_joined_pipes = force_joined_pipes;
+			break;
+		}
+
+		fallthrough;
 	default:
 		return -EINVAL;
 	}