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 15:03:52 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     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,
        robin.murphy@....com
Subject: Re: [PATCH 1/2] arm64: dts: rockchip: Fix multiple thermal zones
 conflict in rk3399.dtsi

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.


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