openwrt/target/linux/generic/backport-6.1/815-v6.6-2-leds-turris-omnia-Drop-unnecessary-mutex-locking.patch

From 8f3d612a5c949489b2860b74ff34c5914a9216dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Beh=C3=BAn?= <kabel@kernel.org>
Date: Wed, 2 Aug 2023 18:07:43 +0200
Subject: [PATCH 2/6] leds: turris-omnia: Drop unnecessary mutex locking
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Do not lock driver mutex in the global LED panel brightness sysfs
accessors brightness_show() and brightness_store().

The mutex locking is unnecessary here. The I2C transfers are guarded by
I2C core locking mechanism, and the LED commands itself do not interfere
with other commands.

Fixes: 089381b27abe ("leds: initial support for Turris Omnia LEDs")
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230802160748.11208-2-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>
---
 drivers/leds/leds-turris-omnia.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

--- a/drivers/leds/leds-turris-omnia.c
+++ b/drivers/leds/leds-turris-omnia.c
@@ -156,12 +156,9 @@ static ssize_t brightness_show(struct de
 			       char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
-	struct omnia_leds *leds = i2c_get_clientdata(client);
 	int ret;
 
-	mutex_lock(&leds->lock);
 	ret = i2c_smbus_read_byte_data(client, CMD_LED_GET_BRIGHTNESS);
-	mutex_unlock(&leds->lock);
 
 	if (ret < 0)
 		return ret;
@@ -173,7 +170,6 @@ static ssize_t brightness_store(struct d
 				const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
-	struct omnia_leds *leds = i2c_get_clientdata(client);
 	unsigned long brightness;
 	int ret;
 
@@ -183,15 +179,10 @@ static ssize_t brightness_store(struct d
 	if (brightness > 100)
 		return -EINVAL;
 
-	mutex_lock(&leds->lock);
 	ret = i2c_smbus_write_byte_data(client, CMD_LED_SET_BRIGHTNESS,
 					(u8)brightness);
-	mutex_unlock(&leds->lock);
 
-	if (ret < 0)
-		return ret;
-
-	return count;
+	return ret < 0 ? ret : count;
 }
 static DEVICE_ATTR_RW(brightness);