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Subject: Re: [PATCH v3] thermal/core: Clear all mitigation when thermal zone
 is disabled
To:     Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Amit Kucheria <amitk@kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Thara Gopinath <thara.gopinath@linaro.org>,
        Matthias Kaehlcke <mka@chromium.org>
Cc:     linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1641581806-32550-1-git-send-email-quic_manafm@quicinc.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <927aca29-fca7-bdf9-9ad6-2599125ca1b4@linaro.org>
Date:   Sun, 23 Jan 2022 21:51:00 +0100
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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 ?


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@quicinc.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;
>  }
> 


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