From 195e41ac71e4f7d78504592c7e8f31ab1a6b53ff Mon Sep 17 00:00:00 2001 From: Vadim Pasternak Date: Wed, 30 Jul 2025 23:17:15 +0300 Subject: [PATCH] hwmon: mlxreg-fan: Prevent fans from getting stuck at 0 RPM [ Upstream commit 1180c79fbf36e4c02e76ae4658509523437e52a4 ] The fans controlled by the driver can get stuck at 0 RPM if they are configured below a 20% duty cycle. The driver tries to avoid this by enforcing a minimum duty cycle of 20%, but this is done after the fans are registered with the thermal subsystem. This is too late as the thermal subsystem can set their current state before the driver is able to enforce the minimum duty cycle. Fix by setting the minimum duty cycle before registering the fans with the thermal subsystem. Fixes: d7efb2ebc7b3 ("hwmon: (mlxreg-fan) Extend driver to support multiply cooling devices") Reported-by: Nikolay Aleksandrov Tested-by: Nikolay Aleksandrov Signed-off-by: Ido Schimmel Signed-off-by: Vadim Pasternak Link: https://lore.kernel.org/r/20250730201715.1111133-1-vadimp@nvidia.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/mlxreg-fan.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/hwmon/mlxreg-fan.c b/drivers/hwmon/mlxreg-fan.c index 96017cc8da7e..7514d5766104 100644 --- a/drivers/hwmon/mlxreg-fan.c +++ b/drivers/hwmon/mlxreg-fan.c @@ -551,15 +551,14 @@ static int mlxreg_fan_cooling_config(struct device *dev, struct mlxreg_fan *fan) if (!pwm->connected) continue; pwm->fan = fan; + /* Set minimal PWM speed. */ + pwm->last_hwmon_state = MLXREG_FAN_PWM_DUTY2STATE(MLXREG_FAN_MIN_DUTY); pwm->cdev = devm_thermal_of_cooling_device_register(dev, NULL, mlxreg_fan_name[i], pwm, &mlxreg_fan_cooling_ops); if (IS_ERR(pwm->cdev)) { dev_err(dev, "Failed to register cooling device\n"); return PTR_ERR(pwm->cdev); } - - /* Set minimal PWM speed. */ - pwm->last_hwmon_state = MLXREG_FAN_PWM_DUTY2STATE(MLXREG_FAN_MIN_DUTY); } return 0;