From 0767335233a8cbab00bbe260a4e4bd380c7677fd Mon Sep 17 00:00:00 2001 From: Manuel Fombuena Date: Thu, 2 Jul 2026 23:34:37 +0100 Subject: [PATCH] leds: st1202: Disable channel when brightness is set to zero When brightness_set() is called with LED_OFF, only the ILED register is zeroed; the channel enable bit is left set from probe time. A hardware channel enabled with ILED=0 still draws a small residual current, causing a dim glow even when the LED is supposed to be off. Fix this by splitting st1202_channel_set() into a lockless inner function __st1202_channel_set() and a locking wrapper, then calling the inner function from brightness_set() while it already holds the mutex. The channel is now disabled when value is zero and re-enabled when non-zero, in the same lock region as the ILED write. Fixes: 259230378c65 ("leds: Add LED1202 I2C driver") Signed-off-by: Manuel Fombuena Assisted-by: Claude:claude-sonnet-4-6 Link: https://patch.msgid.link/GV1PR08MB8497F11B30FE7D74CAA25135C5F52@GV1PR08MB8497.eurprd08.prod.outlook.com Signed-off-by: Lee Jones --- drivers/leds/leds-st1202.c | 68 ++++++++++++++++++++++---------------- 1 file changed, 39 insertions(+), 29 deletions(-) diff --git a/drivers/leds/leds-st1202.c b/drivers/leds/leds-st1202.c index 4909985ade04..2ecd36aae336 100644 --- a/drivers/leds/leds-st1202.c +++ b/drivers/leds/leds-st1202.c @@ -128,39 +128,11 @@ static int st1202_duration_pattern_write(struct st1202_chip *chip, int pattern, st1202_prescalar_to_miliseconds(value)); } -static void st1202_brightness_set(struct led_classdev *led_cdev, - enum led_brightness value) -{ - struct st1202_led *led = cdev_to_st1202_led(led_cdev); - struct st1202_chip *chip = led->chip; - - guard(mutex)(&chip->lock); - - for (int patt = 0; patt < ST1202_MAX_PATTERNS; patt++) - st1202_pwm_pattern_write(chip, led->led_num, patt, ST1202_PATTERN_PWM_FULL); - st1202_write_reg(chip, ST1202_ILED_REG0 + led->led_num, value); -} - -static enum led_brightness st1202_brightness_get(struct led_classdev *led_cdev) -{ - struct st1202_led *led = cdev_to_st1202_led(led_cdev); - struct st1202_chip *chip = led->chip; - u8 value = 0; - - guard(mutex)(&chip->lock); - - st1202_read_reg(chip, ST1202_ILED_REG0 + led->led_num, &value); - - return value; -} - -static int st1202_channel_set(struct st1202_chip *chip, int led_num, bool active) +static int __st1202_channel_set(struct st1202_chip *chip, int led_num, bool active) { u8 chan_low, chan_high; int ret; - guard(mutex)(&chip->lock); - if (led_num <= 7) { ret = st1202_read_reg(chip, ST1202_CHAN_ENABLE_LOW, &chan_low); if (ret < 0) @@ -188,6 +160,40 @@ static int st1202_channel_set(struct st1202_chip *chip, int led_num, bool active return 0; } +static int st1202_channel_set(struct st1202_chip *chip, int led_num, bool active) +{ + guard(mutex)(&chip->lock); + + return __st1202_channel_set(chip, led_num, active); +} + +static void st1202_brightness_set(struct led_classdev *led_cdev, + enum led_brightness value) +{ + struct st1202_led *led = cdev_to_st1202_led(led_cdev); + struct st1202_chip *chip = led->chip; + + guard(mutex)(&chip->lock); + + for (int patt = 0; patt < ST1202_MAX_PATTERNS; patt++) + st1202_pwm_pattern_write(chip, led->led_num, patt, ST1202_PATTERN_PWM_FULL); + st1202_write_reg(chip, ST1202_ILED_REG0 + led->led_num, value); + __st1202_channel_set(chip, led->led_num, !!value); +} + +static enum led_brightness st1202_brightness_get(struct led_classdev *led_cdev) +{ + struct st1202_led *led = cdev_to_st1202_led(led_cdev); + struct st1202_chip *chip = led->chip; + u8 value = 0; + + guard(mutex)(&chip->lock); + + st1202_read_reg(chip, ST1202_ILED_REG0 + led->led_num, &value); + + return value; +} + static int st1202_led_set(struct led_classdev *ldev, enum led_brightness value) { struct st1202_led *led = cdev_to_st1202_led(ldev); @@ -257,6 +263,10 @@ static int st1202_led_pattern_set(struct led_classdev *ldev, if (ret != 0) return ret; + ret = __st1202_channel_set(chip, led->led_num, true); + if (ret != 0) + return ret; + ret = st1202_write_reg(chip, ST1202_CONFIG_REG, (ST1202_CONFIG_REG_PATSR | ST1202_CONFIG_REG_PATS | ST1202_CONFIG_REG_SHFT)); if (ret != 0)