linux-kernel - Re: [PATCH v3] thermal/core: Clear all mitigation when thermal zone is disabled

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Date:   Mon, 24 Jan 2022 01:05:35 +0000
From:   "Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
To:     "Zhang, Rui" <rui.zhang@...el.com>,
        "thara.gopinath@...aro.org" <thara.gopinath@...aro.org>,
        "mka@...omium.org" <mka@...omium.org>,
        "quic_manafm@...cinc.com" <quic_manafm@...cinc.com>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "amitk@...nel.org" <amitk@...nel.org>
CC:     "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] thermal/core: Clear all mitigation when thermal zone
 is disabled

On Sun, 2022-01-23 at 21:51 +0100, Daniel Lezcano wrote:
> 
> Hi Manaf,
> 
> semantically speaking disabling a thermal zone would be to detach the
> thermal zone from its governor and stop the monitoring.
> 
> May be add the functions
> 
>  - thermal_governor_attach(struct thermal_zone_device *tzd)
>    {
>         ...
>         if (tz->governor && tz->governor->bind_to_tz) {
>                 if (tz->governor->bind_to_tz(tz)) {
>         }
>         ...
>    }
> 
>  - thermal_governor_detach(struct thermal_zone_device *tzd)
>    {
>         ...
>         if (tz->governor && tz->governor->unbind_from_tz)
>                 tz->governor->unbind_from_tz(tz);
>         ...
>    }
> 
> And add in the step_wise and power_allocator the reset of the
> governor's
> data as well as the cooling device instances in the unbind_from_tz()
> callback
> 
> Then, thermal_zone_device_enable() attaches and
> thermal_zone_device_disable() detaches the governor.
> 
> Does it make sense ?
This is better.

Thanks,
Srinivas

> 
> 
> On 07/01/2022 19:56, Manaf Meethalavalappu Pallikunhi wrote:
> > Whenever a thermal zone is in trip violated state, there is a
> > chance
> > that the same thermal zone mode can be disabled either via thermal
> > core API or via thermal zone sysfs. Once it is disabled, the
> > framework
> > bails out any re-evaluation of thermal zone. It leads to a case
> > where
> > if it is already in mitigation state, it will stay the same state
> > until it is re-enabled.
> > 
> > To avoid above mentioned issue, on thermal zone disable request
> > reset thermal zone and clear mitigation for each trip explicitly.
> > 
> > Signed-off-by: Manaf Meethalavalappu Pallikunhi
> > <quic_manafm@...cinc.com>
> > ---
> >  drivers/thermal/thermal_core.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/thermal/thermal_core.c
> > b/drivers/thermal/thermal_core.c
> > index 51374f4..e288c82 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -447,10 +447,18 @@ static int
> > thermal_zone_device_set_mode(struct thermal_zone_device *tz,
> >  
> >         thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
> >  
> > -       if (mode == THERMAL_DEVICE_ENABLED)
> > +       if (mode == THERMAL_DEVICE_ENABLED) {
> >                 thermal_notify_tz_enable(tz->id);
> > -       else
> > +       } else {
> > +               int trip;
> > +
> > +               /* make sure all previous throttlings are cleared
> > */
> > +               thermal_zone_device_init(tz);
> > +               for (trip = 0; trip < tz->trips; trip++)
> > +                       handle_thermal_trip(tz, trip);
> > +
> >                 thermal_notify_tz_disable(tz->id);
> > +       }
> >  
> >         return ret;
> >  }
> > 
> 
>