Re: [PATCH v2 6/6] hwmon: (adt7470) Add thermal zone sensor support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The background update thread holds a private mutex during a multi-second sleep, which will severely stall the thermal subsystem polling.
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--- Patch [6]: [PATCH v2 6/6] hwmon: (adt7470) Add thermal zone sensor support ---
commit c1655de2721e60975758432b0053b21f699a5803
Author: Luiz Angelo Daros de Luca <luizluca@gmail.com>

hwmon: (adt7470) Add thermal zone sensor support

This commit exposes the ADT7470 external temperature sensors to the thermal
framework using the HWMON_C_REGISTER_TZ flag.

> diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
> index aaae14a421cd8..595a8f934d60a 100644
> --- a/drivers/hwmon/adt7470.c
> +++ b/drivers/hwmon/adt7470.c
> @@ -1251,6 +1251,8 @@ static const struct hwmon_ops adt7470_hwmon_ops = {
>  };
>  
>  static const struct hwmon_channel_info * const adt7470_info[] = {
> +	HWMON_CHANNEL_INFO(chip,
> +			   HWMON_C_REGISTER_TZ),

[Severity: High]
Could exposing this sensor to the thermal framework cause a regression by
stalling the thermal workqueue?

The thermal subsystem will automatically poll this sensor via adt7470_read(),
which acquires data->lock.

Concurrently, the driver's background kthread adt7470_update_thread() holds
this exact lock while executing msleep_interruptible() for up to 2 seconds
in adt7470_read_temperatures():

drivers/hwmon/adt7470.c:adt7470_update_thread() {
    ...
    mutex_lock(&data->lock);
    adt7470_read_temperatures(data);
    mutex_unlock(&data->lock);
    ...
}

drivers/hwmon/adt7470.c:adt7470_read_temperatures() {
    ...
    res = msleep_interruptible((data->num_temp_sensors >= 0 ?
                                data->num_temp_sensors * 200 :
                                TEMP_COLLECTION_TIME));
    ...
}

Will the thermal workqueue block for up to 2 seconds when trying to read the
temperature, risking a stall in thermal management for other zones sharing
the same workqueue?

>  	HWMON_CHANNEL_INFO(temp,
>  			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX | HWMON_T_ALARM,

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260717-adt7470_thermalzone-v2-0-a55147958fad@gmail.com?part=6