[PATCH v2] leds: lp5860: fix LED teardown ordering using devm_add_action_or_reset()

[kr494167@gmail.com]

From: Surendra Singh Chouhan <kr494167@gmail.com>

The driver previously disabled the chip in its remove callback before
devres unregistered the LEDs. LED unregistration turns the LEDs off
through the driver brightness callback, which accessed disabled hardware.

Fix this by registering a devm action via devm_add_action_or_reset()
immediately after enabling the chip in lp5860_device_init(). Due to devm
LIFO (Last-In, First-Out) teardown ordering, devm will automatically
unregister all multicolor LEDs before the devm action disables the chip.

This allows removing lp5860_device_remove() and lp5860_remove() completely.
In addition, convert mutex_init() to devm_mutex_init() to ensure proper
devm-managed mutex lifecycle.

Fixes: f0a66563aa2d ("leds: Add support for TI LP5860 LED driver chip")
Signed-off-by: Surendra Singh Chouhan <kr494167@gmail.com>
---
v2:
 - Use full name "Surendra Singh Chouhan" in From header and Signed-off-by.
 - Convert chip disable sequence to devm_add_action_or_reset() as suggested by Lee Jones, allowing removal of lp5860_device_remove() and lp5860_remove() entirely.
 - Use devm_mutex_init() for lock initialization.

 drivers/leds/rgb/leds-lp5860-core.c | 35 ++++++++++++-----------------
 drivers/leds/rgb/leds-lp5860-spi.c  | 14 +++---------
 drivers/leds/rgb/leds-lp5860.h      |  1 -
 3 files changed, 17 insertions(+), 33 deletions(-)

diff --git a/drivers/leds/rgb/leds-lp5860-core.c b/drivers/leds/rgb/leds-lp5860-core.c
index fd0e2f6e6e0f..bbe299e36ad5 100644
--- a/drivers/leds/rgb/leds-lp5860-core.c
+++ b/drivers/leds/rgb/leds-lp5860-core.c
@@ -188,6 +188,13 @@ static int lp5860_init_dt(struct lp5860 *lp)
 	return 0;
 }
 
+static void lp5860_disable_action(void *data)
+{
+	struct lp5860 *lp = data;
+
+	lp5860_chip_enable(lp, LP5860_CHIP_DISABLE);
+}
+
 int lp5860_device_init(struct device *dev)
 {
 	struct lp5860 *lp = dev_get_drvdata(dev);
@@ -197,38 +204,24 @@ int lp5860_device_init(struct device *dev)
 	if (ret)
 		return ret;
 
+	ret = devm_add_action_or_reset(dev, lp5860_disable_action, lp);
+	if (ret)
+		return ret;
+
 	/*
 	 * Set to 8-bit PWM data without VSYNC.
 	 * Data is sent out for display instantly after received.
 	 */
-	mutex_lock(&lp->lock);
+	guard(mutex)(&lp->lock);
 	ret = regmap_update_bits(lp->regmap, LP5860_REG_DEV_INITIAL, LP5860_MODE_MASK,
 				 LP5860_MODE_1 << LP5860_MODE_SHIFT);
 	if (ret)
-		goto err_disable;
-	mutex_unlock(&lp->lock);
-
-	ret = lp5860_init_dt(lp);
-	if (ret)
-		goto err_disable;
-
-	return 0;
+		return ret;
 
-err_disable:
-	mutex_unlock(&lp->lock);
-	lp5860_chip_enable(lp, LP5860_CHIP_DISABLE);
-	return ret;
+	return lp5860_init_dt(lp);
 }
 EXPORT_SYMBOL_GPL(lp5860_device_init);
 
-void lp5860_device_remove(struct device *dev)
-{
-	struct lp5860 *lp = dev_get_drvdata(dev);
-
-	lp5860_chip_enable(lp, LP5860_CHIP_DISABLE);
-}
-EXPORT_SYMBOL_GPL(lp5860_device_remove);
-
 MODULE_AUTHOR("Steffen Trumtrar <kernel@pengutronix.de>");
 MODULE_DESCRIPTION("TI LP5860 RGB LED core driver");
 MODULE_LICENSE("GPL");
diff --git a/drivers/leds/rgb/leds-lp5860-spi.c b/drivers/leds/rgb/leds-lp5860-spi.c
index 5e0c44854a68..13ad90362d5f 100644
--- a/drivers/leds/rgb/leds-lp5860-spi.c
+++ b/drivers/leds/rgb/leds-lp5860-spi.c
@@ -61,22 +61,15 @@ static int lp5860_probe(struct spi_device *spi)
 				     "Failed to initialise Regmap.\n");
 
 	lp5860->dev = dev;
-	mutex_init(&lp5860->lock);
+	ret = devm_mutex_init(dev, &lp5860->lock);
+	if (ret)
+		return ret;
 
 	spi_set_drvdata(spi, lp5860);
 
 	return lp5860_device_init(dev);
 }
 
-static void lp5860_remove(struct spi_device *spi)
-{
-	struct lp5860 *lp5860 = spi_get_drvdata(spi);
-
-	mutex_destroy(&lp5860->lock);
-
-	lp5860_device_remove(&spi->dev);
-}
-
 static const struct of_device_id lp5860_of_match[] = {
 	{ .compatible = "ti,lp5860" },
 	{}
@@ -89,7 +82,6 @@ static struct spi_driver lp5860_driver = {
 		.of_match_table = lp5860_of_match,
 	},
 	.probe	= lp5860_probe,
-	.remove = lp5860_remove,
 };
 module_spi_driver(lp5860_driver);
 
diff --git a/drivers/leds/rgb/leds-lp5860.h b/drivers/leds/rgb/leds-lp5860.h
index 940be0c6e8da..88e327347130 100644
--- a/drivers/leds/rgb/leds-lp5860.h
+++ b/drivers/leds/rgb/leds-lp5860.h
@@ -263,6 +263,5 @@ struct lp5860 {
 };
 
 int lp5860_device_init(struct device *dev);
-void lp5860_device_remove(struct device *dev);
 
 #endif /* _DRIVERS_LEDS_RGB_LP5860_H */
-- 
2.55.0