Re: [PATCH] hwmon: (pwm-fan) Ensure the fan going on in .probe()

[Guenter Roeck <linux@roeck-us.net>]

On 11/30/21 1:22 AM, Billy Tsai wrote:
> Before commit 86585c61972f ("hwmon: (pwm-fan) stop using legacy
> PWM functions and some cleanups") pwm_apply_state() was called
> unconditionally in pwm_fan_probe(). In this commit this direct
> call was replaced by a call to __set_pwm(ct, MAX_PWM) which
> however is a noop if ctx->pwm_value already matches the value to
> set.
> After probe the fan is supposed to run at full speed, and the
> internal driver state suggests it does, but this isn't asserted
> and depending on bootloader and pwm low-level driver, the fan
> might just be off.
> So drop setting pwm_value to MAX_PWM to ensure the check in
> __set_pwm doesn't make it exit early and the fan goes on as
> intended.
> 
> Cc: stable@vger.kernel.org
> Fixes: 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups")
> Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>

I'll apply this patch, but _please_ version your patches in the future
and provide a change log.

Guenter

> ---
>   drivers/hwmon/pwm-fan.c | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 17518b4cab1b..f12b9a28a232 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -336,8 +336,6 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   			return ret;
>   	}
>   
> -	ctx->pwm_value = MAX_PWM;
> -
>   	pwm_init_state(ctx->pwm, &ctx->pwm_state);
>   
>   	/*
>