On Mon, May 23, 2022 at 01:05:11PM +0200, Alexander Stein wrote:
> Regular calls to set_pwm don't hold the mutex, but the upcoming
> update_enable support needs to call set_pwm with the mutex being held.
> So provide the previous behavior in set_pwm (handling the lock), while
> adding __set_pwm which assumes the lock being held.
>
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
For my reference:
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/hwmon/pwm-fan.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 04af24268963..fcc1b7b55a65 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -152,14 +152,12 @@ static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> unsigned long period;
> int ret = 0;
>
> - mutex_lock(&ctx->lock);
> -
> if (pwm > 0) {
> period = state->period;
> state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1), MAX_PWM);
> ret = pwm_apply_state(ctx->pwm, state);
> if (ret)
> - goto exit_set_pwm_err;
> + return ret;
> ret = pwm_fan_power_on(ctx);
> } else {
> ret = pwm_fan_power_off(ctx);
> @@ -167,8 +165,17 @@ static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> if (!ret)
> ctx->pwm_value = pwm;
>
> -exit_set_pwm_err:
> + return ret;
> +}
> +
> +static int set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> +{
> + int ret;
> +
> + mutex_lock(&ctx->lock);
> + ret = __set_pwm(ctx, pwm);
> mutex_unlock(&ctx->lock);
> +
> return ret;
> }
>
> @@ -192,7 +199,7 @@ static int pwm_fan_write(struct device *dev, enum hwmon_sensor_types type,
> if (val < 0 || val > MAX_PWM)
> return -EINVAL;
>
> - ret = __set_pwm(ctx, val);
> + ret = set_pwm(ctx, val);
> if (ret)
> return ret;
>
> @@ -280,7 +287,7 @@ pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
> if (state == ctx->pwm_fan_state)
> return 0;
>
> - ret = __set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
> + ret = set_pwm(ctx, ctx->pwm_fan_cooling_levels[state]);
> if (ret) {
> dev_err(&cdev->device, "Cannot set pwm!\n");
> return ret;
> @@ -400,7 +407,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
> pwm_init_state(ctx->pwm, &ctx->pwm_state);
>
> /*
> - * __set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
> + * set_pwm assumes that MAX_PWM * (period - 1) fits into an unsigned
> * long. Check this here to prevent the fan running at a too low
> * frequency.
> */
> @@ -410,7 +417,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
> }
>
> /* Set duty cycle to maximum allowed and enable PWM output */
> - ret = __set_pwm(ctx, MAX_PWM);
> + ret = set_pwm(ctx, MAX_PWM);
> if (ret) {
> dev_err(dev, "Failed to configure PWM: %d\n", ret);
> return ret;
