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([2a01:e34:ed2f:f020:28c8:8dc7:5312:94e2]) by smtp.googlemail.com with ESMTPSA id v8sm14992443wrc.29.2021.06.13.11.19.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Jun 2021 11:19:33 -0700 (PDT) Subject: Re: [PATCH v1 03/10] ARM: tegra: acer-a500: Bump thermal trips by 10C To: Dmitry Osipenko , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Cc: Thierry Reding , Jonathan Hunter , Agneli , Paul Fertser , Svyatoslav Ryhel , linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210510202600.12156-1-digetx@gmail.com> <20210510202600.12156-4-digetx@gmail.com> <20210514211601.GA1969@qmqm.qmqm.pl> From: Daniel Lezcano Message-ID: <1abadc69-1dd1-5939-c089-37a84be4781b@linaro.org> Date: Sun, 13 Jun 2021 20:19:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog