linux-kernel - Re: [PATCH] drivers: thermal: Reset previous low and high trip during thermal zone init

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Date:   Tue, 16 Nov 2021 20:31:38 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>,
        Manaf Meethalavalappu Pallikunhi <manafm@...eaurora.org>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers: thermal: Reset previous low and high trip during
 thermal zone init

On Fri, Nov 5, 2021 at 7:49 PM Thara Gopinath <thara.gopinath@...aro.org> wrote:
>
>
>
> On 11/2/21 4:00 PM, Manaf Meethalavalappu Pallikunhi wrote:
> > During the suspend is in process, thermal_zone_device_update bails out
> > thermal zone re-evaluation for any sensor trip violation without
> > setting next valid trip to that sensor. It assumes during resume
> > it will re-evaluate same thermal zone and update trip. But when it is
> > in suspend temperature goes down and on resume path while updating
> > thermal zone if temperature is less than previously violated trip,
> > thermal zone set trip function evaluates the same previous high and
> > previous low trip as new high and low trip. Since there is no change
> > in high/low trip, it bails out from thermal zone set trip API without
> > setting any trip. It leads to a case where sensor high trip or low
> > trip is disabled forever even though thermal zone has a valid high
> > or low trip.
> >
> > During thermal zone device init, reset thermal zone previous high
> > and low trip. It resolves above mentioned scenario.
> >
> > Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@...eaurora.org>
>
> Reviewed-by: Thara Gopinath <thara.gopinath@...aro.org>
>
> --
> Warm Regards
> Thara (She/Her/Hers)
>
> > ---
> >   drivers/thermal/thermal_core.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index 21db445..2b7a0b4 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -477,6 +477,8 @@ static void thermal_zone_device_init(struct thermal_zone_device *tz)
> >   {
> >       struct thermal_instance *pos;
> >       tz->temperature = THERMAL_TEMP_INVALID;
> > +     tz->prev_low_trip = -INT_MAX;
> > +     tz->prev_high_trip = INT_MAX;
> >       list_for_each_entry(pos, &tz->thermal_instances, tz_node)
> >               pos->initialized = false;
> >   }

Applied as 5.16-rc2 material, thanks!