drm: Improve the output_poll_changed description

this callback was used by drm_kms_helper_hotplug_event()

V2: (Thanks for Daniel's suggestions)
- remove the FIXME below.since with the drm_client
- infrastructure and the generic fbdev emulation we've
- resolved this all very neatly now.

V3: Add comments that This hook is deprecated
- new implementation methods instead of this hook

v4: used by drm_kms_helper_hotplug_event()
- drm_fb_helper_hotplug_changed() is not found
instead by drm_kms_helper_hotplug_event()

Signed-off-by: ZhiJie.Zhang <zhangzhijie@loongson.cn>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210903032402.11935-1-zhangzhijie@loongson.cn

include/drm/drm_mode_config.h

@@ -103,14 +103,13 @@ struct drm_mode_config_funcs {
 	 * Callback used by helpers to inform the driver of output configuration
 	 * changes.
 	 *
-	 * Drivers implementing fbdev emulation with the helpers can call
-	 * drm_fb_helper_hotplug_changed from this hook to inform the fbdev
-	 * helper of output changes.
+	 * Drivers implementing fbdev emulation use drm_kms_helper_hotplug_event()
+	 * to call this hook to inform the fbdev helper of output changes.
 	 *
-	 * FIXME:
-	 *
-	 * Except that there's no vtable for device-level helper callbacks
-	 * there's no reason this is a core function.
+	 * This hook is deprecated, drivers should instead use
+	 * drm_fbdev_generic_setup() which takes care of any necessary
+	 * hotplug event forwarding already without further involvement by
+	 * the driver.
 	 */
 	void (*output_poll_changed)(struct drm_device *dev);