linux-kernel - Re: [PATCH v1 03/10] ARM: tegra: acer-a500: Bump thermal trips by 10C

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Message-ID: <8091014b-fe1b-9c4c-7a91-6aae5b4037e5@linaro.org>
Date:   Tue, 15 Jun 2021 15:05:21 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Agneli <poczt@...tonmail.ch>, Paul Fertser <fercerpav@...il.com>,
        Svyatoslav Ryhel <clamor95@...il.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 03/10] ARM: tegra: acer-a500: Bump thermal trips by 10C

On 15/06/2021 14:53, Dmitry Osipenko wrote:
> 13.06.2021 21:19, Daniel Lezcano пишет:
>> On 13/06/2021 02:25, Dmitry Osipenko wrote:
>>
>> [ ... ]
>>
>>>> You should set the trip points close to the functioning boundary
>>>> temperature given in the hardware specification whatever the resulting
>>>> heating effect is on the device.
>>>>
>>>> The thermal zone is there to protect the silicon and the system from a
>>>> wild reboot.
>>>>
>>>> If the Nexus 7 is too hot after the changes, then you may act on the
>>>> sources of the heat. For instance, set the the highest OPP to turbo or
>>>> remove it, or, if there is one, change the thermal daemon to reduce the
>>>> overall power consumption.
>>>> In case you are interested in: https://lwn.net/Articles/839318/
>>>
>>> The DTPM is a very interesting approach. For now Tegra still misses some
>>> basics in mainline kernel which have a higher priority, so I think it
>>> should be good enough to perform the in-kernel thermal management for
>>> the starter. We may consider a more complex solutions later on if will
>>> be necessary.
>>>
>>> What I'm currently thinking to do is:
>>>
>>> 1. Set up the trips of SoC/CPU core thermal zones in accordance to the
>>> silicon limits.
>>>
>>> 2. Set up the skin trips in accordance to the device limits.
>>>
>>> The breached skin trips will cause a mild throttling, while the SoC/CPU
>>> trips will be allowed to cause the severe throttling. Does this sound
>>> good to you?
>>
>> The skin temperature must be managed from userspace. The kernel is
>> unable to do a smart thermal management given different thermal zones
>> but if the goal is to go forward and prevent the tablet to be hot
>> temporarily until the other hardware support is there, I think it is
>> acceptable.
> 
> The current goal is to get maximum from what we already have, thank you.

maximum of performance or maximum of mitigation ?


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