linux-kernel - [PATCH 3/3] leds: lm3692x: Disable chip on brightness 0

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Message-Id: <e1dc56c07235063a9c0afbfc8c227b92b39ec3d4.1577272495.git.agx@sigxcpu.org>
Date:   Wed, 25 Dec 2019 12:16:39 +0100
From:   Guido Günther <agx@...xcpu.org>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Dan Murphy <dmurphy@...com>,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] 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 <agx@...xcpu.org>
---
 drivers/leds/leds-lm3692x.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/leds/leds-lm3692x.c b/drivers/leds/leds-lm3692x.c
index d1bd9ae4e7ab..183614744b92 100644
--- a/drivers/leds/leds-lm3692x.c
+++ b/drivers/leds/leds-lm3692x.c
@@ -117,6 +117,7 @@ struct lm3692x_led {
 	int model_id;
 
 	u8 boost_ctrl, brightness_ctrl;
+	bool enabled;
 };
 
 static const struct reg_default lm3692x_reg_defs[] = {
@@ -170,6 +171,9 @@ static int lm3692x_leds_enable(struct lm3692x_led *led)
 	int enable_state;
 	int ret, reg_ret;
 
+	if (led->enabled)
+		return 0;
+
 	if (led->regulator) {
 		ret = regulator_enable(led->regulator);
 		if (ret) {
@@ -271,6 +275,7 @@ static int lm3692x_leds_enable(struct lm3692x_led *led)
 	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");
@@ -292,6 +297,9 @@ static int lm3692x_leds_disable(struct lm3692x_led *led)
 {
 	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",
@@ -309,6 +317,7 @@ static int lm3692x_leds_disable(struct lm3692x_led *led)
 				"Failed to disable regulator: %d\n", ret);
 	}
 
+	led->enabled = false;
 	return ret;
 }
 
@@ -322,6 +331,13 @@ static int lm3692x_brightness_set(struct led_classdev *led_cdev,
 
 	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) {
 		dev_err(&led->client->dev, "Cannot read/clear faults: %d\n",
-- 
2.23.0