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hwmon: (gpio-fan) Update the speed cache before dropping the PM reference

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set_fan_speed() writes the GPIO control value before dropping the runtime
PM reference when stopping the fan. pm_runtime_put_sync() decrements the
usage count even when suspending the device fails, but the error return
currently leaves speed_index at the previous running speed.

A request for that same running speed then returns success without
changing the GPIOs or taking a runtime PM reference. Retrying the stop
instead drops a reference the driver no longer owns and can trigger a
runtime PM usage count underflow warning.

Update speed_index after writing the GPIOs and before dropping the PM
reference. The initial same-speed check already excludes a stopped fan,
so a zero target is sufficient to identify the transition that needs a
PM put. Preserve the PM error return and the CONFIG_PM=n exception.

This keeps the cached control state and PM reference ownership consistent
without restoring running GPIOs after a possibly partial supply failure.
It does not clear persistent runtime PM errors or claim that a failing
regulator has successfully powered off.

Fixes: 0d01110e63 ("hwmon: (gpio-fan) Add regulator support")
Cc: stable@vger.kernel.org
Signed-off-by: Baek Kyu, Kim <pocj8ur4in@gmail.com>
Link: https://patch.msgid.link/20261031095039.11683-1-pocj8ur4in@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Baek Kyu, Kim 2026-10-31 18:50:39 +09:00 committed by Guenter Roeck
parent 7cd6053807
commit f324179e6c
1 changed files with 4 additions and 3 deletions
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7
drivers/hwmon/gpio-fan.c
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@ -150,7 +150,10 @@ static int set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
__set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
if (fan_data->speed_index > 0 && speed_index == 0) {
/* The GPIOs have changed, and a PM put drops the reference on error. */
fan_data->speed_index = speed_index;
if (speed_index == 0) {
int ret;
ret = pm_runtime_put_sync(fan_data->dev);
@ -158,8 +161,6 @@ static int set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
return ret;
}
fan_data->speed_index = speed_index;
return 0;
}