video: pwm_backlight: use regulator_set_enable_if_allowed

With the commit 4fcba5d ("regulator: implement basic reference
counter") the return value of regulator_set_enable may be EALREADY or
EBUSY for fixed/gpio regulators and may be further expanded on all
regulators.

Change to use the more relaxed regulator_set_enable_if_allowed to
continue if regulator already was enabled or disabled.

Signed-off-by: Svyatoslav Ryhel <[email protected]>

drivers/video/pwm_backlight.c

@@ -100,8 +100,8 @@ static int enable_sequence(struct udevice *dev, int seq)
 			plat = dev_get_uclass_plat(priv->reg);
 			log_debug("Enable '%s', regulator '%s'/'%s'\n",
 				  dev->name, priv->reg->name, plat->name);
-			ret = regulator_set_enable(priv->reg, true);
-			if (ret) {
+			ret = regulator_set_enable_if_allowed(priv->reg, true);
+			if (ret && ret != -ENOSYS) {
 				log_debug("Cannot enable regulator for PWM '%s'\n",
 					  dev->name);
 				return log_ret(ret);
@@ -181,11 +181,10 @@ static int pwm_backlight_set_brightness(struct udevice *dev, int percent)
 	}
 	if (disable) {
 		dm_gpio_set_value(&priv->enable, 0);
-		if (priv->reg) {
-			ret = regulator_set_enable(priv->reg, false);
-			if (ret)
-				return log_ret(ret);
-		}
+		ret = regulator_set_enable_if_allowed(priv->reg, false);
+		if (ret && ret != -ENOSYS)
+			return log_ret(ret);
+
 		priv->enabled = false;
 	}