linux-kernel - Re: [PATCH 1/2] arm64: dts: rockchip: Fix multiple thermal zones conflict in rk3399.dtsi

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Date:   Fri, 14 Jun 2019 16:30:13 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Robin Murphy <robin.murphy@....com>,
        Heiko Stuebner <heiko@...ech.de>
Cc:     linux-kernel@...r.kernel.org, edubezval@...il.com,
        manivannan.sadhasivam@...aro.org, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Philipp Tomsich <philipp.tomsich@...obroma-systems.com>,
        Christoph Muellner <christoph.muellner@...obroma-systems.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Emil Renner Berthing <kernel@...il.dk>,
        Randy Li <ayaka@...lik.info>,
        Tony Xie <tony.xie@...k-chips.com>,
        Vicente Bergas <vicencb@...il.com>,
        Klaus Goger <klaus.goger@...obroma-systems.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/Rockchip SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC support" 
        <linux-rockchip@...ts.infradead.org>, dianders@...omium.org,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH 1/2] arm64: dts: rockchip: Fix multiple thermal zones
 conflict in rk3399.dtsi

On 14/06/2019 16:02, Robin Murphy wrote:
> On 14/06/2019 14:03, Daniel Lezcano wrote:
>> On 14/06/2019 11:35, Heiko Stuebner wrote:
>>> Hi Daniel,
>>>
>>> Am Dienstag, 4. Juni 2019, 18:57:57 CEST schrieb Daniel Lezcano:
>>>> Currently the common thermal zones definitions for the rk3399 assumes
>>>> multiple thermal zones are supported by the governors. This is not the
>>>> case and each thermal zone has its own governor instance acting
>>>> individually without collaboration with other governors.
>>>>
>>>> As the cooling device for the CPU and the GPU thermal zones is the
>>>> same, each governors take different decisions for the same cooling
>>>> device leading to conflicting instructions and an erratic behavior.
>>>>
>>>> As the cooling-maps is about to become an optional property, let's
>>>> remove the cpu cooling device map from the GPU thermal zone.
>>>>
>>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>>>> ---
>>>>   arch/arm64/boot/dts/rockchip/rk3399.dtsi | 9 ---------
>>>>   1 file changed, 9 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> index 196ac9b78076..e1357e0f60f7 100644
>>>> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
>>>> @@ -821,15 +821,6 @@
>>>>                       type = "critical";
>>>>                   };
>>>>               };
>>>> -
>>>> -            cooling-maps {
>>>> -                map0 {
>>>> -                    trip = <&gpu_alert0>;
>>>> -                    cooling-device =
>>>> -                        <&cpu_b0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
>>>> -                        <&cpu_b1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
>>>> -                };
>>>> -            };
>>>>           };
>>>>       };
>>>
>>> my knowledge of the thermal framework is not that big, but what about
>>> the
>>> rk3399-devices which further detail the cooling-maps like
>>> rk3399-gru-kevin
>>> and the rk3399-nanopc-t4 with its fan-handling in the cooling-maps?
>>
>> The rk3399-gru-kevin is correct.
>>
>> The rk3399-nanopc-t4 is not correct because the cpu and the gpu are
>> sharing the same cooling device (the fan). There are different
>> configurations:
>>
>> 1. The cpu cooling device for the CPU and the fan for the GPU
>>
>> 2. Different trip points on the CPU thermal zone, eg. one to for the CPU
>> cooling device and another one for the fan.
>>
>> There are some variant for the above. If this board is not on battery,
>> you may want to give priority to the throughput, so activate the fan
>> first and then cool down the CPU. Or if you are on battery, you may want
>> to invert the trip points.
>>
>> In any case, it is not possible to share the same cooling device for
>> different thermal zones.
> 
> OK, thanks for the clarification. I'll get my board set up again to
> figure out the best fix for rk3399-nanopc-t4 (FWIW most users are
> probably just using passive cooling or a plain DC fan anyway). You might
> want to raise this issue with the maintainers of
> arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi, since the
> everything-shared-by-everything approach in there was what I used as a
> reference.

Cc'ed: Kukjin Kim and Krzysztof Kozlowski

Easy :)


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