drm/panel: boe-tv101wum-nl6: Support enabling a 3.3V rail

The auo,b101uan08.3 panel (already supported by this driver) has
a 3.3V rail that needs to be turned on. For previous users of
this panel this voltage was directly output by pmic. On a new
user (the not-yet-upstream sc7180-trogdor-mrbland board) we need
to turn the 3.3V rail on. Add support in the driver for this.
Signed-off-by: yangcong <yangcong5@huaqin.corp-partner.google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210914032252.3770756-2-yangcong5@huaqin.corp-partner.google.com

drivers/gpu/drm/panel/panel-boe-tv101wum-nl6.c

@@ -45,6 +45,7 @@ struct boe_panel {
 	const struct panel_desc *desc;
 
 	enum drm_panel_orientation orientation;
+	struct regulator *pp3300;
 	struct regulator *pp1800;
 	struct regulator *avee;
 	struct regulator *avdd;
@@ -511,6 +512,7 @@ static int boe_panel_unprepare(struct drm_panel *panel)
 		gpiod_set_value(boe->enable_gpio, 0);
 		usleep_range(5000, 7000);
 		regulator_disable(boe->pp1800);
+		regulator_disable(boe->pp3300);
 	} else {
 		gpiod_set_value(boe->enable_gpio, 0);
 		usleep_range(500, 1000);
@@ -518,6 +520,7 @@ static int boe_panel_unprepare(struct drm_panel *panel)
 		regulator_disable(boe->avdd);
 		usleep_range(5000, 7000);
 		regulator_disable(boe->pp1800);
+		regulator_disable(boe->pp3300);
 	}
 
 	boe->prepared = false;
@@ -536,6 +539,10 @@ static int boe_panel_prepare(struct drm_panel *panel)
 	gpiod_set_value(boe->enable_gpio, 0);
 	usleep_range(1000, 1500);
 
+	ret = regulator_enable(boe->pp3300);
+	if (ret < 0)
+		return ret;
+
 	ret = regulator_enable(boe->pp1800);
 	if (ret < 0)
 		return ret;
@@ -767,6 +774,10 @@ static int boe_panel_add(struct boe_panel *boe)
 	if (IS_ERR(boe->avee))
 		return PTR_ERR(boe->avee);
 
+	boe->pp3300 = devm_regulator_get(dev, "pp3300");
+	if (IS_ERR(boe->pp3300))
+		return PTR_ERR(boe->pp3300);
+
 	boe->pp1800 = devm_regulator_get(dev, "pp1800");
 	if (IS_ERR(boe->pp1800))
 		return PTR_ERR(boe->pp1800);