linux-kernel - Re: [PATCH] hwmon: (pwm-fan) Explicitly switch off fan power when setting pwm1

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Message-ID: <20221014165129.GA234611@roeck-us.net>
Date:   Fri, 14 Oct 2022 09:51:29 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc:     Jean Delvare <jdelvare@...e.com>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (pwm-fan) Explicitly switch off fan power when
 setting pwm1_enable to 0

On Thu, Oct 13, 2022 at 03:59:51PM +0200, Matthias Schiffer wrote:
> When pwm1_enable is changed from 1 to 0 while pwm1 == 0, the regulator
> is not switched off as expected. The reason is that when the fan is
> already off, ctx->enabled is false, so pwm_fan_power_off() will be a
> no-op.
> 
> Handle this case explicitly in pwm_fan_update_enable() by calling
> pwm_fan_switch_power() directly.
> 
> Fixes: b99152d4f04b ("hwmon: (pwm-fan) Switch regulator dynamically")
> Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/pwm-fan.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index dc3d9a22d917..83a347ca35da 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -257,7 +257,10 @@ static int pwm_fan_update_enable(struct pwm_fan_ctx *ctx, long val)
>  
>  	if (val == 0) {
>  		/* Disable pwm-fan unconditionally */
> -		ret = __set_pwm(ctx, 0);
> +		if (ctx->enabled)
> +			ret = __set_pwm(ctx, 0);
> +		else
> +			ret = pwm_fan_switch_power(ctx, false);
>  		if (ret)
>  			ctx->enable_mode = old_val;
>  		pwm_fan_update_state(ctx, 0);