drm/panel: drop return code from drm_panel_detach()

There are no errors that can be reported by this function,
so drop the return code.
Fix the only bridge driver that checked the return result.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190804201637.1240-14-sam@ravnborg.org

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

@@ -1780,8 +1780,7 @@ void analogix_dp_unbind(struct analogix_dp_device *dp)
 	if (dp->plat_data->panel) {
 		if (drm_panel_unprepare(dp->plat_data->panel))
 			DRM_ERROR("failed to turnoff the panel\n");
-		if (drm_panel_detach(dp->plat_data->panel))
-			DRM_ERROR("failed to detach the panel\n");
+		drm_panel_detach(dp->plat_data->panel);
 	}
 
 	drm_dp_aux_unregister(&dp->aux);

drivers/gpu/drm/drm_panel.c

@@ -123,15 +123,11 @@ EXPORT_SYMBOL(drm_panel_attach);
  *
  * This function should not be called by the panel device itself. It
  * is only for the drm device that called drm_panel_attach().
- *
- * Return: 0 on success or a negative error code on failure.
  */
-int drm_panel_detach(struct drm_panel *panel)
+void drm_panel_detach(struct drm_panel *panel)
 {
 	panel->connector = NULL;
 	panel->drm = NULL;
-
-	return 0;
 }
 EXPORT_SYMBOL(drm_panel_detach);
 

include/drm/drm_panel.h

@@ -153,7 +153,7 @@ int drm_panel_add(struct drm_panel *panel);
 void drm_panel_remove(struct drm_panel *panel);
 
 int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector);
-int drm_panel_detach(struct drm_panel *panel);
+void drm_panel_detach(struct drm_panel *panel);
 
 int drm_panel_prepare(struct drm_panel *panel);
 int drm_panel_unprepare(struct drm_panel *panel);