drm/panel: seiko-43wvf1g: 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/20191207140353.23967-20-sam@ravnborg.org

drivers/gpu/drm/panel/panel-seiko-43wvf1g.c

@@ -6,7 +6,6 @@
  * Based on Panel Simple driver by Thierry Reding <treding@nvidia.com>
  */
 
-#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -46,7 +45,6 @@ struct seiko_panel {
 	bool prepared;
 	bool enabled;
 	const struct seiko_panel_desc *desc;
-	struct backlight_device *backlight;
 	struct regulator *dvdd;
 	struct regulator *avdd;
 };
@@ -127,12 +125,6 @@ static int seiko_panel_disable(struct drm_panel *panel)
 	if (!p->enabled)
 		return 0;
 
-	if (p->backlight) {
-		p->backlight->props.power = FB_BLANK_POWERDOWN;
-		p->backlight->props.state |= BL_CORE_FBBLANK;
-		backlight_update_status(p->backlight);
-	}
-
 	p->enabled = false;
 
 	return 0;
@@ -196,12 +188,6 @@ static int seiko_panel_enable(struct drm_panel *panel)
 	if (p->enabled)
 		return 0;
 
-	if (p->backlight) {
-		p->backlight->props.state &= ~BL_CORE_FBBLANK;
-		p->backlight->props.power = FB_BLANK_UNBLANK;
-		backlight_update_status(p->backlight);
-	}
-
 	p->enabled = true;
 
 	return 0;
@@ -245,7 +231,6 @@ static const struct drm_panel_funcs seiko_panel_funcs = {
 static int seiko_panel_probe(struct device *dev,
 					const struct seiko_panel_desc *desc)
 {
-	struct device_node *backlight;
 	struct seiko_panel *panel;
 	int err;
 
@@ -265,18 +250,13 @@ static int seiko_panel_probe(struct device *dev,
 	if (IS_ERR(panel->avdd))
 		return PTR_ERR(panel->avdd);
 
-	backlight = of_parse_phandle(dev->of_node, "backlight", 0);
-	if (backlight) {
-		panel->backlight = of_find_backlight_by_node(backlight);
-		of_node_put(backlight);
-
-		if (!panel->backlight)
-			return -EPROBE_DEFER;
-	}
-
 	drm_panel_init(&panel->base, dev, &seiko_panel_funcs,
 		       DRM_MODE_CONNECTOR_DPI);
 
+	err = drm_panel_of_backlight(&panel->base);
+	if (err)
+		return err;
+
 	err = drm_panel_add(&panel->base);
 	if (err < 0)
 		return err;
@@ -291,11 +271,7 @@ static int seiko_panel_remove(struct platform_device *pdev)
 	struct seiko_panel *panel = dev_get_drvdata(&pdev->dev);
 
 	drm_panel_remove(&panel->base);
-
-	seiko_panel_disable(&panel->base);
-
-	if (panel->backlight)
-		put_device(&panel->backlight->dev);
+	drm_panel_disable(&panel->base);
 
 	return 0;
 }
@@ -304,7 +280,7 @@ static void seiko_panel_shutdown(struct platform_device *pdev)
 {
 	struct seiko_panel *panel = dev_get_drvdata(&pdev->dev);
 
-	seiko_panel_disable(&panel->base);
+	drm_panel_disable(&panel->base);
 }
 
 static const struct display_timing seiko_43wvf1g_timing = {