leds: lm3692x: Disable chip on brightness 0

Otherwise there's a noticeable glow even with brightness 0. Also
turning off the regulator can save additional power.

Signed-off-by: Guido Günther <[e-mail]>
Signed-off-by: Pavel Machek <[e-mail]>

drivers/leds/leds-lm3692x.c

···
 	int led_enable;
 	int model_id;
 
-	u8 boost_ctrl;
+	u8 boost_ctrl, brightness_ctrl;
+	bool enabled;
 };
 
 static const struct reg_default lm3692x_reg_defs[] = {
···
 {
 	int enable_state;
 	int ret, reg_ret;
+
+	if (led->enabled)
+		return 0;
 
 	if (led->regulator) {
 		ret = regulator_enable(led->regulator);
···
 	ret = regmap_update_bits(led->regmap, LM3692X_EN, LM3692X_ENABLE_MASK,
 				 enable_state | LM3692X_DEVICE_EN);
 
+	led->enabled = true;
 	return ret;
 out:
 	dev_err(&led->client->dev, "Fail writing initialization values\n");
···
 {
 	int ret;
 
+	if (!led->enabled)
+		return 0;
+
 	ret = regmap_update_bits(led->regmap, LM3692X_EN, LM3692X_DEVICE_EN, 0);
 	if (ret) {
 		dev_err(&led->client->dev, "Failed to disable regulator: %d\n",
···
 				"Failed to disable regulator: %d\n", ret);
 	}
 
+	led->enabled = false;
 	return ret;
 }
 
···
 	int led_brightness_lsb = (brt_val >> 5);
 
 	mutex_lock(&led->lock);
+
+	if (brt_val == 0) {
+		ret = lm3692x_leds_disable(led);
+		goto out;
+	} else {
+		lm3692x_leds_enable(led);
+	}
 
 	ret = lm3692x_fault_check(led);
 	if (ret) {