Subject: Re: [PATCH v5 06/11] hwmon: Add Apple Silicon SMC hwmon driver

From: Dan Carpenter <[email-masked]>
Date: Fri, 28 Nov 2025 11:10:39 +0300

On Wed, Nov 12, 2025 at 09:16:52PM +1000, James Calligeros wrote:
> +static int macsmc_hwmon_populate_sensors(struct macsmc_hwmon *hwmon,
> +					 struct device_node *hwmon_node)
> +{
> +	struct device_node *key_node __maybe_unused;

The for_each_child_of_node_with_prefix() macros declare key_node so this
declaration is never used so far as I can see.  I thought Sparse had a
warning where we declared shadow variables where two variables have the
same name but it doesn't complain here. #strange

> +	struct macsmc_hwmon_sensor *sensor;
> +	u32 n_current = 0, n_fan = 0, n_power = 0, n_temperature = 0, n_voltage = 0;
> +
> +	for_each_child_of_node_with_prefix(hwmon_node, key_node, "current-") {
                                                       ^^^^^^^^

regards,
dan carpenter

> +		n_current++;
> +	}
> +
> +	if (n_current) {
> +		hwmon->curr.sensors = devm_kcalloc(hwmon->dev, n_current,
> +						   sizeof(struct macsmc_hwmon_sensor), GFP_KERNEL);
> +		if (!hwmon->curr.sensors)
> +			return -ENOMEM;
> +
> +		for_each_child_of_node_with_prefix(hwmon_node, key_node, "current-") {
> +			sensor = &hwmon->curr.sensors[hwmon->curr.count];
> +			if (!macsmc_hwmon_create_sensor(hwmon->dev, hwmon->smc, key_node, sensor)) {
> +				sensor->attrs = HWMON_C_INPUT;
> +
> +				if (*sensor->label)
> +					sensor->attrs |= HWMON_C_LABEL;
> +
> +				hwmon->curr.count++;
> +			}
> +		}
> +	}
> +
> +	for_each_child_of_node_with_prefix(hwmon_node, key_node, "fan-") {
> +		n_fan++;
> +	}
> +
> +	if (n_fan) {
> +		hwmon->fan.fans = devm_kcalloc(hwmon->dev, n_fan,
> +					       sizeof(struct macsmc_hwmon_fan), GFP_KERNEL);
> +		if (!hwmon->fan.fans)
> +			return -ENOMEM;
> +
> +		for_each_child_of_node_with_prefix(hwmon_node, key_node, "fan-") {
> +			if (!macsmc_hwmon_create_fan(hwmon->dev, hwmon->smc, key_node,
> +						     &hwmon->fan.fans[hwmon->fan.count]))
> +				hwmon->fan.count++;
> +		}
> +	}
> +
> +	for_each_child_of_node_with_prefix(hwmon_node, key_node, "power-") {
> +		n_power++;
> +	}
> +
> +	if (n_power) {
> +		hwmon->power.sensors = devm_kcalloc(hwmon->dev, n_power,
> +						    sizeof(struct macsmc_hwmon_sensor), GFP_KERNEL);
> +		if (!hwmon->power.sensors)
> +			return -ENOMEM;
> +
> +		for_each_child_of_node_with_prefix(hwmon_node, key_node, "power-") {
> +			sensor = &hwmon->power.sensors[hwmon->power.count];
> +			if (!macsmc_hwmon_create_sensor(hwmon->dev, hwmon->smc, key_node, sensor)) {
> +				sensor->attrs = HWMON_P_INPUT;
> +
> +				if (*sensor->label)
> +					sensor->attrs |= HWMON_P_LABEL;
> +
> +				hwmon->power.count++;
> +			}
> +		}
> +	}
> +
> +	for_each_child_of_node_with_prefix(hwmon_node, key_node, "temperature-") {
> +		n_temperature++;
> +	}
> +
> +	if (n_temperature) {
> +		hwmon->temp.sensors = devm_kcalloc(hwmon->dev, n_temperature,
> +						   sizeof(struct macsmc_hwmon_sensor), GFP_KERNEL);
> +		if (!hwmon->temp.sensors)
> +			return -ENOMEM;
> +
> +		for_each_child_of_node_with_prefix(hwmon_node, key_node, "temperature-") {
> +			sensor = &hwmon->temp.sensors[hwmon->temp.count];
> +			if (!macsmc_hwmon_create_sensor(hwmon->dev, hwmon->smc, key_node, sensor)) {
> +				sensor->attrs = HWMON_T_INPUT;
> +
> +				if (*sensor->label)
> +					sensor->attrs |= HWMON_T_LABEL;
> +
> +				hwmon->temp.count++;
> +			}
> +		}
> +	}
> +
> +	for_each_child_of_node_with_prefix(hwmon_node, key_node, "voltage-") {
> +		n_voltage++;
> +	}
> +
> +	if (n_voltage) {
> +		hwmon->volt.sensors = devm_kcalloc(hwmon->dev, n_voltage,
> +						   sizeof(struct macsmc_hwmon_sensor), GFP_KERNEL);
> +		if (!hwmon->volt.sensors)
> +			return -ENOMEM;
> +
> +		for_each_child_of_node_with_prefix(hwmon_node, key_node, "volt-") {
> +			sensor = &hwmon->temp.sensors[hwmon->temp.count];
> +			if (!macsmc_hwmon_create_sensor(hwmon->dev, hwmon->smc, key_node, sensor)) {
> +				sensor->attrs = HWMON_I_INPUT;
> +
> +				if (*sensor->label)
> +					sensor->attrs |= HWMON_I_LABEL;
> +
> +				hwmon->volt.count++;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +}