drm/probe-helper: use drm_kms_helper_connector_hotplug_event

If an hotplug event only updates a single connector, use
drm_kms_helper_connector_hotplug_event instead of
drm_kms_helper_hotplug_event.

Changes in v4:
- Simplify loop logic (Ville, Sam)
- Update drm_connector_helper_hpd_irq_event (Maxime)

Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018084707.32253-6-contact@emersion.fr

drivers/gpu/drm/drm_probe_helper.c

@@ -888,7 +888,7 @@ bool drm_connector_helper_hpd_irq_event(struct drm_connector *connector)
 	mutex_unlock(&dev->mode_config.mutex);
 
 	if (changed) {
-		drm_kms_helper_hotplug_event(dev);
+		drm_kms_helper_connector_hotplug_event(connector);
 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Sent hotplug event\n",
 			    connector->base.id,
 			    connector->name);
@@ -927,9 +927,9 @@ EXPORT_SYMBOL(drm_connector_helper_hpd_irq_event);
  */
 bool drm_helper_hpd_irq_event(struct drm_device *dev)
 {
-	struct drm_connector *connector;
+	struct drm_connector *connector, *first_changed_connector = NULL;
 	struct drm_connector_list_iter conn_iter;
-	bool changed = false;
+	int changed = 0;
 
 	if (!dev->mode_config.poll_enabled)
 		return false;
@@ -941,16 +941,25 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
 		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
 			continue;
 
-		if (check_connector_changed(connector))
-			changed = true;
+		if (check_connector_changed(connector)) {
+			if (!first_changed_connector) {
+				drm_connector_get(connector);
+				first_changed_connector = connector;
+			}
+
+			changed++;
+		}
 	}
 	drm_connector_list_iter_end(&conn_iter);
 	mutex_unlock(&dev->mode_config.mutex);
 
-	if (changed) {
+	if (changed == 1)
+		drm_kms_helper_connector_hotplug_event(first_changed_connector);
+	else if (changed > 0)
 		drm_kms_helper_hotplug_event(dev);
-		DRM_DEBUG_KMS("Sent hotplug event\n");
-	}
+
+	if (first_changed_connector)
+		drm_connector_put(first_changed_connector);
 
 	return changed;
 }