drm/omapdrm: Use of_find_backlight helper

Replace of_find_backlight_by_node and of the code around it
with of_find_backlight helper to avoid repetition of code.

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/eb914313f9d0e58d81572ccd3c718a573a891bd7.1516810726.git.meghana.madhyastha@gmail.com

drivers/gpu/drm/omapdrm/displays/panel-dpi.c

@@ -157,7 +157,6 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 {
 	struct panel_drv_data *ddata = platform_get_drvdata(pdev);
 	struct device_node *node = pdev->dev.of_node;
-	struct device_node *bl_node;
 	struct omap_dss_device *in;
 	int r;
 	struct display_timing timing;
@@ -183,39 +182,28 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 	if (IS_ERR(ddata->vcc_supply))
 		return PTR_ERR(ddata->vcc_supply);
 
-	bl_node = of_parse_phandle(node, "backlight", 0);
-	if (bl_node) {
-		ddata->backlight = of_find_backlight_by_node(bl_node);
-		of_node_put(bl_node);
+	ddata->backlight = devm_of_find_backlight(&pdev->dev);
 
-		if (!ddata->backlight)
-			return -EPROBE_DEFER;
-	}
+	if (IS_ERR(ddata->backlight))
+		return PTR_ERR(ddata->backlight);
 
 	r = of_get_display_timing(node, "panel-timing", &timing);
 	if (r) {
 		dev_err(&pdev->dev, "failed to get video timing\n");
-		goto error_free_backlight;
+		return r;
 	}
 
 	videomode_from_timing(&timing, &ddata->vm);
 
 	in = omapdss_of_find_source_for_first_ep(node);
 	if (IS_ERR(in)) {
 		dev_err(&pdev->dev, "failed to find video source\n");
-		r = PTR_ERR(in);
-		goto error_free_backlight;
+		return PTR_ERR(in);
 	}
 
 	ddata->in = in;
 
 	return 0;
-
-error_free_backlight:
-	if (ddata->backlight)
-		put_device(&ddata->backlight->dev);
-
-	return r;
 }
 
 static int panel_dpi_probe(struct platform_device *pdev)
@@ -270,9 +258,6 @@ static int __exit panel_dpi_remove(struct platform_device *pdev)
 
 	omap_dss_put_device(in);
 
-	if (ddata->backlight)
-		put_device(&ddata->backlight->dev);
-
 	return 0;
 }