linux-kernel - Re: [PATCH 2/5] hwmon: (ina3221) Return -ENODATA for two alarms attributes

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Date:   Wed, 17 Oct 2018 12:46:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Nicolin Chen <nicoleotsuka@...il.com>
Cc:     jdelvare@...e.com, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] hwmon: (ina3221) Return -ENODATA for two alarms
 attributes

On Tue, Oct 16, 2018 at 06:24:23PM -0700, Nicolin Chen wrote:
> There is nothing critically wrong to read these two attributes
> without having a is_enabled() check at this point. But reading
> the MASK_ENABLE register would clear the CVRF bit according to
> the datasheet. So it'd be safer to fence for disabled channels
> in order to add pm runtime feature.
> 
> Signed-off-by: Nicolin Chen <nicoleotsuka@...il.com>
> ---
>  drivers/hwmon/ina3221.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> index d61688f04594..3e98b59108ee 100644
> --- a/drivers/hwmon/ina3221.c
> +++ b/drivers/hwmon/ina3221.c
> @@ -200,6 +200,8 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
>  		return 0;
>  	case hwmon_curr_crit_alarm:
>  	case hwmon_curr_max_alarm:
> +		if (!ina3221_is_enabled(ina, channel))
> +			return -ENODATA;

Makes sense, but can you check what the sensors command does with this ?
If it bails out I'd rather have the code return 0 and no error (after all,
the sensor is disabled, so any alarm would be bogus).

Thanks,
Guenter

>  		ret = regmap_field_read(ina->fields[reg], &regval);
>  		if (ret)
>  			return ret;
> -- 
> 2.17.1
>