linux-kernel - Re: [PATCH v1] thermal: trip: Send trip change notifications on all trip updates

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Message-ID: <CAJZ5v0ic_=2wvge1T7YmGe5icR5dPxrvKy2N4gXP+KMievobmA@mail.gmail.com>
Date:   Wed, 6 Dec 2023 17:01:37 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Lukasz Luba <lukasz.luba@....com>
Subject: Re: [PATCH v1] thermal: trip: Send trip change notifications on all
 trip updates

Hi Daniel,

On Wed, Dec 6, 2023 at 3:38 PM Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
>
>
> Hi Rafael,
>
> On 05/12/2023 20:18, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > The _store callbacks of the trip point temperature and hysteresis sysfs
> > attributes invoke thermal_notify_tz_trip_change() to send a notification
> > regarding the trip point change, but when trip points are updated by the
> > platform firmware, trip point change notifications are not sent.
> >
> > To make the behavior after a trip point change more consistent,
> > modify all of the 3 places where trip point temperature is updated
> > to use a new function called thermal_zone_set_trip_temp() for this
> > purpose and make that function call thermal_notify_tz_trip_change().
> >
> > Note that trip point hysteresis can only be updated via sysfs and
> > trip_point_hyst_store() calls thermal_notify_tz_trip_change() already,
> > so this code path need not be changed.
>
> Why the ACPI driver is not calling thermal_zone_device_update() after
> changing the trip point like the other drivers?

It calls that function, but because it may update multiple trips in
one go, it does that after all of the updates are done, via
acpi_thermal_check_fn().

> It would make sense to have the thermal framework to be notified about
> this change and check if there is a trip violation, no ?

It is notified as noted above, but not synchronously.