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Subject: Re: [RFC PATCH 0/4] thermal: Introduce support for monitoring falling
 temperature
To:     Thara Gopinath <thara.gopinath@linaro.org>, rui.zhang@intel.com,
        robh+dt@kernel.org
Cc:     linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20200710135154.181454-1-thara.gopinath@linaro.org>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <7437ee89-e76d-0c82-9860-5c6076ad8a30@linaro.org>
Date:   Mon, 13 Jul 2020 17:03:04 +0200
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On 10/07/2020 15:51, Thara Gopinath wrote:
> Thermal framework today supports monitoring for rising temperatures and
> subsequently initiating cooling action in case of a thermal trip point
> being crossed. There are scenarios where a SoC need some warming action to
> be activated if the temperature falls below a cetain permissible limit.
> Since warming action can be considered mirror opposite of cooling action,
> most of the thermal framework can be re-used to achieve this.
> 
> This patch series is yet another attempt to add support for monitoring
> falling temperature in thermal framework. Unlike the first attempt[1]
> (where a new property was added to thermal trip point binding to indicate
> direction of temperature monitoring), this series introduces a new trip
> point type (THERMAL_TRIP_COLD) to indicate a trip point at which falling
> temperature monitoring must be triggered. This patch series uses Daniel
> Lezcano's recently added thermal genetlink interface[2] to notify userspace
> of falling temperature and rising temperature at the cold trip point. This
> will enable a user space engine to trigger the relevant mitigation for
> falling temperature. At present, no support is added to any of the thermal
> governors to monitor and mitigate falling temperature at the cold trip
> point;rather all governors return doing nothing if triggered for a cold
> trip point. As future extension, monitoring of falling temperature can be
> added to the relevant thermal governor. 

I agree we need a cold trip point in order to introduce the functioning
temperature range in the thermal framework.

Rui, what is your opinion ?


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