Re: [PATCH v4 0/2] iio: temperature: Add support for NXP P3T175x temperature sensors

[Guenter Roeck]

On 10/8/25 03:07, Lakshay Piplani wrote:
> This patch adds support for the P3T1750/P3T1755 temperature sensors under the IIO subsystem.
>
> P3T1750/P3T1755 support two operational modes:
> 1. Comparator Mode
> 2. Interrupt (Latched) Mode
>
> The HWMON subsystem is more suitable for implementing drivers for comparator mode operations.
> Reason:
>    - Temperature thresholds can be polled and exposed via sysfs.
>    - Register reads do not clear status, allowing safe alarm state derivation.
>    - Matches existing drivers under hwmon.
>
> The IIO subsystem is more suitable for implementing drivers for interrupt (latched) mode operations.
> Reason:
>    - Interrupt mode uses edge-triggered ALERT/IBI signal interrupts, which can be pushed to user space using iio_push_event.
>    - IIO’s event API (IIO_EV_TYPE_THRESH) supports timestamped rising/falling edge events.
>    - I3C IBI integration maps naturally to IIO’s event push model.
>    - No persistent alarm bits are available; so polling in HWMON may result in  missing events.

This is just wrong. Interrupt support can just as well be implemented
in a hwmon driver.

Guenter