Re: [PATCH v3] arm64: dts: rockchip: add thermal fan control to rockpro64

[Robin Murphy]

On 2021-08-13 13:59, Daniel Lezcano wrote:
> On 30/07/2021 17:17, Peter Geis wrote:
> > The rockpro64 had a fan node since
> > commit 5882d65c1691 ("arm64: dts: rockchip: Add PWM fan for RockPro64")
> > however it was never tied into the thermal driver for automatic control.
> >
> > Add the links to the thermal node to permit the kernel to handle this
> > automatically.
> > Borrowed from the (rk3399-khadas-edge.dtsi).
> >
> > Signed-off-by: Peter Geis <pgwipeout@xxxxxxxxx>
> > ---
> >
> > Changelog:
> > v3:
> > Removed the gpu nodes to prevent in-fighting (thanks Robin!)
> >
> > v2:
> > Adjusted fan setpoints for less noise
> >
> >   .../boot/dts/rockchip/rk3399-rockpro64.dtsi   | 29 +++++++++++++++++++
> >   1 file changed, 29 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
> > index 6bff8db7d33e..83db4ca67334 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
> > @@ -69,6 +69,7 @@ diy_led: led-1 {
> >   
> >   	fan: pwm-fan {
> >   		compatible = "pwm-fan";
> > +		cooling-levels = <0 100 150 200 255>;
> >   		#cooling-cells = <2>;
> >   		fan-supply = <&vcc12v_dcin>;
> >   		pwms = <&pwm1 0 50000 0>;
> > @@ -245,6 +246,34 @@ &cpu_b1 {
> >   	cpu-supply = <&vdd_cpu_b>;
> >   };
> >   
> > +&cpu_thermal {
> > +	trips {
> > +		cpu_warm: cpu_warm {
> > +			temperature = <55000>;
> > +			hysteresis = <2000>;
> > +			type = "active";
> > +		};
> > +
> > +		cpu_hot: cpu_hot {
> > +			temperature = <65000>;
> > +			hysteresis = <2000>;
> > +			type = "active";
> > +		};
> > +	};
> > +
>
> Why two trip points ?
>
> Why not one functioning temperature and no lower / upper limits for the
> cooling maps ?

Certainly when I first did this for NanoPC-T4, IIRC it was to avoid the 
fan ramping up too eagerly, since level 1 for my fan is effectively 
silent but still cools enough to let a moderate load eventually settle 
to a steady state below the second trip.

Robin.

> > +	cooling-maps {
> > +		map2 {
> > +			trip = <&cpu_warm>;
> > +			cooling-device = <&fan THERMAL_NO_LIMIT 1>;
> > +		};
> > +
> > +		map3 {
> > +			trip = <&cpu_hot>;
> > +			cooling-device = <&fan 2 THERMAL_NO_LIMIT>;
> > +		};
> > +	};
> > +};
> > +
> >   &emmc_phy {
> >   	status = "okay";
> >   };