linux-kernel - Re: [PATCH 3/3] hwmon: (sht3x)add new non-stardard sysfs interface

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Message-ID: <7594a5cd-9ef1-4093-20e3-b824cb91194d@roeck-us.net>
Date:   Wed, 14 Jun 2023 06:04:14 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     JuenKit Yip <JuenKit_Yip@...mail.com>, jdelvare@...e.com
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] hwmon: (sht3x)add new non-stardard sysfs interface

On 6/13/23 23:28, JuenKit Yip wrote:
> add "repeatability" interface to sysfs, it could be
> read or written to control the sensor.
> 
> Signed-off-by: JuenKit Yip <JuenKit_Yip@...mail.com>
> ---
>   Documentation/hwmon/sht3x.rst |  7 +++++++
>   drivers/hwmon/sht3x.c         | 29 +++++++++++++++++++++++++++++
>   2 files changed, 36 insertions(+)
> 
> diff --git a/Documentation/hwmon/sht3x.rst b/Documentation/hwmon/sht3x.rst
> index 2c87c8f58..3dc4b9c14 100644
> --- a/Documentation/hwmon/sht3x.rst
> +++ b/Documentation/hwmon/sht3x.rst
> @@ -83,4 +83,11 @@ heater_enable:      heater enable, heating element removes excess humidity from
>   update_interval:    update interval, 0 for single shot, interval in msec
>   		    for periodic measurement. If the interval is not supported
>   		    by the sensor, the next faster interval is chosen
> +repeatability:      write or read repeatability, the higher repeatability means
> +                    the longer measurement duration, the lower noise level and
> +                    the larger energy consumption:

s/the//g

> +
> +                        - 0: low repeatability
> +                        - 1: medium repeatability
> +                        - 2: high repeatability
>   =================== ============================================================
> diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
> index eb968b9d3..209090a48 100644
> --- a/drivers/hwmon/sht3x.c
> +++ b/drivers/hwmon/sht3x.c
> @@ -642,6 +642,33 @@ static ssize_t update_interval_store(struct device *dev,
>   	return count;
>   }
>   
> +static ssize_t repeatability_show(struct device *dev,
> +				  struct device_attribute *attr,
> +				  char *buf)
> +{
> +	struct sht3x_data *data = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "%d\n", data->repeatability);
> +}
> +
> +static ssize_t repeatability_store(struct device *dev,
> +				     struct device_attribute *attr,
> +				     const char *buf,
> +				     size_t count)
> +{
> +	u8 val;
> +	struct sht3x_data *data = dev_get_drvdata(dev);
> +
> +	val = kstrtou8(buf, 0, &val);
> +	if (val)
> +		return val;

You need a separate ret variable with type int.

> +
> +	val = clamp_val(val, low_repeatability, high_repeatability);

This should not be clamped; the accepted values are well defined,
and this is not a range.

> +	data->repeatability = val;
> +
> +	return count;
> +}
> +
>   static SENSOR_DEVICE_ATTR_RO(temp1_input, temp1_input, 0);
>   static SENSOR_DEVICE_ATTR_RO(humidity1_input, humidity1_input, 0);
>   static SENSOR_DEVICE_ATTR_RW(temp1_max, temp1_limit, limit_max);
> @@ -658,6 +685,7 @@ static SENSOR_DEVICE_ATTR_RO(temp1_alarm, temp1_alarm, 0);
>   static SENSOR_DEVICE_ATTR_RO(humidity1_alarm, humidity1_alarm, 0);
>   static SENSOR_DEVICE_ATTR_RW(heater_enable, heater_enable, 0);
>   static SENSOR_DEVICE_ATTR_RW(update_interval, update_interval, 0);
> +static SENSOR_DEVICE_ATTR_RW(repeatability, repeatability, 0);
>   
>   static struct attribute *sht3x_attrs[] = {
>   	&sensor_dev_attr_temp1_input.dev_attr.attr,
> @@ -674,6 +702,7 @@ static struct attribute *sht3x_attrs[] = {
>   	&sensor_dev_attr_humidity1_alarm.dev_attr.attr,
>   	&sensor_dev_attr_heater_enable.dev_attr.attr,
>   	&sensor_dev_attr_update_interval.dev_attr.attr,
> +	&sensor_dev_attr_repeatability.dev_attr.attr,
>   	NULL
>   };
>