drm/panel: kingdisplay-kd097d04: use drm_panel backlight support

Use the backlight support in drm_panel to simplify the driver
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191207140353.23967-12-sam@ravnborg.org

drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c

@@ -3,7 +3,6 @@
  * Copyright (c) 2017, Fuzhou Rockchip Electronics Co., Ltd
  */
 
-#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -23,7 +22,6 @@ struct kingdisplay_panel {
 	struct drm_panel base;
 	struct mipi_dsi_device *link;
 
-	struct backlight_device *backlight;
 	struct regulator *supply;
 	struct gpio_desc *enable_gpio;
 
@@ -191,8 +189,6 @@ static int kingdisplay_panel_disable(struct drm_panel *panel)
 	if (!kingdisplay->enabled)
 		return 0;
 
-	backlight_disable(kingdisplay->backlight);
-
 	err = mipi_dsi_dcs_set_display_off(kingdisplay->link);
 	if (err < 0)
 		DRM_DEV_ERROR(panel->dev, "failed to set display off: %d\n",
@@ -303,18 +299,10 @@ static int kingdisplay_panel_prepare(struct drm_panel *panel)
 static int kingdisplay_panel_enable(struct drm_panel *panel)
 {
 	struct kingdisplay_panel *kingdisplay = to_kingdisplay_panel(panel);
-	int ret;
 
 	if (kingdisplay->enabled)
 		return 0;
 
-	ret = backlight_enable(kingdisplay->backlight);
-	if (ret) {
-		DRM_DEV_ERROR(panel->dev,
-			      "Failed to enable backlight %d\n", ret);
-		return ret;
-	}
-
 	kingdisplay->enabled = true;
 
 	return 0;
@@ -388,13 +376,13 @@ static int kingdisplay_panel_add(struct kingdisplay_panel *kingdisplay)
 		kingdisplay->enable_gpio = NULL;
 	}
 
-	kingdisplay->backlight = devm_of_find_backlight(dev);
-	if (IS_ERR(kingdisplay->backlight))
-		return PTR_ERR(kingdisplay->backlight);
-
 	drm_panel_init(&kingdisplay->base, &kingdisplay->link->dev,
 		       &kingdisplay_panel_funcs, DRM_MODE_CONNECTOR_DSI);
 
+	err = drm_panel_of_backlight(&kingdisplay->base);
+	if (err)
+		return err;
+
 	return drm_panel_add(&kingdisplay->base);
 }
 
@@ -432,12 +420,12 @@ static int kingdisplay_panel_remove(struct mipi_dsi_device *dsi)
 	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
 	int err;
 
-	err = kingdisplay_panel_unprepare(&kingdisplay->base);
+	err = drm_panel_unprepare(&kingdisplay->base);
 	if (err < 0)
 		DRM_DEV_ERROR(&dsi->dev, "failed to unprepare panel: %d\n",
 			      err);
 
-	err = kingdisplay_panel_disable(&kingdisplay->base);
+	err = drm_panel_disable(&kingdisplay->base);
 	if (err < 0)
 		DRM_DEV_ERROR(&dsi->dev, "failed to disable panel: %d\n", err);
 
@@ -455,8 +443,8 @@ static void kingdisplay_panel_shutdown(struct mipi_dsi_device *dsi)
 {
 	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
 
-	kingdisplay_panel_unprepare(&kingdisplay->base);
-	kingdisplay_panel_disable(&kingdisplay->base);
+	drm_panel_unprepare(&kingdisplay->base);
+	drm_panel_disable(&kingdisplay->base);
 }
 
 static struct mipi_dsi_driver kingdisplay_panel_driver = {