drm/panel: tpo-tpg110: 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: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191207140353.23967-26-sam@ravnborg.org

drivers/gpu/drm/panel/panel-tpo-tpg110.c

@@ -14,13 +14,13 @@
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 
-#include <linux/backlight.h>
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/spi/spi.h>
 
@@ -76,10 +76,6 @@ struct tpg110 {
 	 * @panel: the DRM panel instance for this device
 	 */
 	struct drm_panel panel;
-	/**
-	 * @backlight: backlight for this panel
-	 */
-	struct backlight_device *backlight;
 	/**
 	 * @panel_type: the panel mode as detected
 	 */
@@ -356,8 +352,6 @@ static int tpg110_disable(struct drm_panel *panel)
 	val &= ~TPG110_CTRL2_PM;
 	tpg110_write_reg(tpg, TPG110_CTRL2_PM, val);
 
-	backlight_disable(tpg->backlight);
-
 	return 0;
 }
 
@@ -366,8 +360,6 @@ static int tpg110_enable(struct drm_panel *panel)
 	struct tpg110 *tpg = to_tpg110(panel);
 	u8 val;
 
-	backlight_enable(tpg->backlight);
-
 	/* Take chip out of standby */
 	val = tpg110_read_reg(tpg, TPG110_CTRL2_PM);
 	val |= TPG110_CTRL2_PM;
@@ -432,11 +424,6 @@ static int tpg110_probe(struct spi_device *spi)
 	if (ret)
 		DRM_DEV_ERROR(dev, "no panel height specified\n");
 
-	/* Look for some optional backlight */
-	tpg->backlight = devm_of_find_backlight(dev);
-	if (IS_ERR(tpg->backlight))
-		return PTR_ERR(tpg->backlight);
-
 	/* This asserts the GRESTB signal, putting the display into reset */
 	tpg->grestb = devm_gpiod_get(dev, "grestb", GPIOD_OUT_HIGH);
 	if (IS_ERR(tpg->grestb)) {
@@ -459,6 +446,11 @@ static int tpg110_probe(struct spi_device *spi)
 
 	drm_panel_init(&tpg->panel, dev, &tpg110_drm_funcs,
 		       DRM_MODE_CONNECTOR_DPI);
+
+	ret = drm_panel_of_backlight(&tpg->panel);
+	if (ret)
+		return ret;
+
 	spi_set_drvdata(spi, tpg);
 
 	return drm_panel_add(&tpg->panel);