linux-kernel - Re: [PATCH 1/2] hwmon: (adm1275) Allow setting sample averaging

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Date:   Wed, 23 Feb 2022 09:10:38 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Potin Lai <potin.lai@...ntatw.com>,
        Jean Delvare <jdelvare@...e.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Patrick Williams <patrick@...cx.xyz>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] hwmon: (adm1275) Allow setting sample averaging

On 2/23/22 08:38, Potin Lai wrote:
> Current driver assume PWR_AVG and VI_AVG as 1 by default, and user needs to
> set sample averaging via sysfs manually.
> 
> This patch parses "pwr-avg" and "vi-avg" from device tree, and setting
> sample averaging during probe.
> 
> Signed-off-by: Potin Lai <potin.lai@...ntatw.com>
> ---
>   drivers/hwmon/pmbus/adm1275.c | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
> index d311e0557401..97faff4e3111 100644
> --- a/drivers/hwmon/pmbus/adm1275.c
> +++ b/drivers/hwmon/pmbus/adm1275.c
> @@ -475,6 +475,7 @@ static int adm1275_probe(struct i2c_client *client)
>   	int vindex = -1, voindex = -1, cindex = -1, pindex = -1;
>   	int tindex = -1;
>   	u32 shunt;
> +	u32 avg;
>   
>   	if (!i2c_check_functionality(client->adapter,
>   				     I2C_FUNC_SMBUS_READ_BYTE_DATA
> @@ -756,6 +757,30 @@ static int adm1275_probe(struct i2c_client *client)
>   		return -ENODEV;
>   	}
>   
> +	if (data->have_power_sampling &&
> +	    of_property_read_u32(client->dev.of_node,
> +				"pwr-avg", &avg) == 0) {

Those properties will need a better name and will have to be prefixed
by the chip vendor.

> +		avg = clamp_val(avg, 1, ADM1275_SAMPLES_AVG_MAX);

clamp_val() is inappropriate for devicetree properties.
The property definition needs to include a valid range, and that range
needs to be validated and rejected if invalid.

> +		ret = adm1275_write_pmon_config(data, client,
> +						true, ilog2(avg));
> +		if (ret < 0) {
> +			dev_err(&client->dev, "set pwr-avg failed, ret = %d",
> +				ret);
> +			return ret;
> +		}
> +	}
> +
> +	if (of_property_read_u32(client->dev.of_node, "vi-avg", &avg) == 0) {
> +		avg = clamp_val(avg, 1, ADM1275_SAMPLES_AVG_MAX);
> +		ret = adm1275_write_pmon_config(data, client,
> +						false, ilog2(avg));
> +		if (ret < 0) {
> +			dev_err(&client->dev, "set vi-avg failed, ret = %d",

This needs to be more descriptive, eg "Setting voltage average failed, ...".
Same above.

> +				ret);
> +			return ret;
> +		}
> +	}
> +
>   	if (voindex < 0)
>   		voindex = vindex;
>   	if (vindex >= 0) {