drm/panel: simple: use drm_panel backlight support

Use drm_panel infrastructure for backlight.
Replace direct calls with drm_panel_*() calls
to utilize the drm_panel support.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
cc: 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/20191207140353.23967-4-sam@ravnborg.org

drivers/gpu/drm/panel/panel-simple.c

@@ -21,7 +21,6 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
-#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -105,7 +104,6 @@ struct panel_simple {
 
 	const struct panel_desc *desc;
 
-	struct backlight_device *backlight;
 	struct regulator *supply;
 	struct i2c_adapter *ddc;
 
@@ -236,12 +234,6 @@ static int panel_simple_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);
-	}
-
 	if (p->desc->delay.disable)
 		msleep(p->desc->delay.disable);
 
@@ -307,12 +299,6 @@ static int panel_simple_enable(struct drm_panel *panel)
 	if (p->desc->delay.enable)
 		msleep(p->desc->delay.enable);
 
-	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;
@@ -414,9 +400,9 @@ static void panel_simple_parse_panel_timing_node(struct device *dev,
 
 static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 {
-	struct device_node *backlight, *ddc;
 	struct panel_simple *panel;
 	struct display_timing dt;
+	struct device_node *ddc;
 	int err;
 
 	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
@@ -442,24 +428,13 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 		return err;
 	}
 
-	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;
-	}
-
 	ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0);
 	if (ddc) {
 		panel->ddc = of_find_i2c_adapter_by_node(ddc);
 		of_node_put(ddc);
 
-		if (!panel->ddc) {
-			err = -EPROBE_DEFER;
-			goto free_backlight;
-		}
+		if (!panel->ddc)
+			return -EPROBE_DEFER;
 	}
 
 	if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))
@@ -468,6 +443,10 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	drm_panel_init(&panel->base, dev, &panel_simple_funcs,
 		       desc->connector_type);
 
+	err = drm_panel_of_backlight(&panel->base);
+	if (err)
+		goto free_ddc;
+
 	err = drm_panel_add(&panel->base);
 	if (err < 0)
 		goto free_ddc;
@@ -479,9 +458,6 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 free_ddc:
 	if (panel->ddc)
 		put_device(&panel->ddc->dev);
-free_backlight:
-	if (panel->backlight)
-		put_device(&panel->backlight->dev);
 
 	return err;
 }
@@ -491,25 +467,21 @@ static int panel_simple_remove(struct device *dev)
 	struct panel_simple *panel = dev_get_drvdata(dev);
 
 	drm_panel_remove(&panel->base);
-
-	panel_simple_disable(&panel->base);
-	panel_simple_unprepare(&panel->base);
+	drm_panel_disable(&panel->base);
+	drm_panel_unprepare(&panel->base);
 
 	if (panel->ddc)
 		put_device(&panel->ddc->dev);
 
-	if (panel->backlight)
-		put_device(&panel->backlight->dev);
-
 	return 0;
 }
 
 static void panel_simple_shutdown(struct device *dev)
 {
 	struct panel_simple *panel = dev_get_drvdata(dev);
 
-	panel_simple_disable(&panel->base);
-	panel_simple_unprepare(&panel->base);
+	drm_panel_disable(&panel->base);
+	drm_panel_unprepare(&panel->base);
 }
 
 static const struct drm_display_mode ampire_am_480272h3tmqw_t01h_mode = {