Hello Dragan,

I haven't been able to test patches for a while, but now I have access to
the NanoPC board again, and I've done some tests:

On 10/11/2025 00:23, Dragan Simic wrote:

Hello Hugh,

Thanks for the v2!  Please, see a couple of nitpicks below.

On Sunday, November 09, 2025 20:20 CET, Hugh Cole-Baker [off-list ref] wrote:

quoted

FriendlyELEC offers an optional heatsink and fan addon for the NanoPC-T6
and T6 LTS, which plugs in to the fan connector on the board driven by
pwm1. Add the fan as an active cooling device for the SoC package.

Signed-off-by: Hugh Cole-Baker <redacted>
---
Changes from v1: https://lore.kernel.org/linux-rockchip/20251026194858.92461-1-sigmaris@gmail.com/ (local)
* add the fan to the base board dtsi instead of overlay (Heiko)
* just use 2 trip points for warm and hot temperatures (Dragan, Alexey)

References:
FriendlyELEC heatsink with fan addon:
https://www.friendlyelec.com/index.php?route=product/product&product_id=305
Vendor DT with trip points and PWM duty cycle values:
https://github.com/friendlyarm/kernel-rockchip/blob/4944602540b62f5aad139fe602a76cf7c3176128/arch/arm64/boot/dts/rockchip/rk3588-nanopi6-rev01.dts#L75-L90

I think it would be better to move these references to the patch
description, so they become directly available in the repository.
It might be the best to use the "... [n]" form for the references,
which puts them as close to the backed contents as possible.

Oh, and I think that "arm64: dts: rockchip: Enable active cooling
on NanoPC-T6" as the patch subject would read nicer. :)

quoted

 .../boot/dts/rockchip/rk3588-nanopc-t6.dtsi   | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3588-nanopc-t6.dtsi b/arch/arm64/boot/dts/rockchip/rk3588-nanopc-t6.dtsi
index fafeabe9adf9e..9164a0ee6228e 100644
--- a/arch/arm64/boot/dts/rockchip/rk3588-nanopc-t6.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3588-nanopc-t6.dtsi

@@ -11,6 +11,7 @@
 #include <dt-bindings/input/input.h>
 #include <dt-bindings/pinctrl/rockchip.h>
 #include <dt-bindings/soc/rockchip,vop2.h>
+#include <dt-bindings/thermal/thermal.h>
 #include <dt-bindings/usb/pd.h>
 #include "rk3588.dtsi"
 

@@ -89,6 +90,14 @@ usr_led: led-1 {
 		};
 	};
 
+	fan: pwm-fan {
+		compatible = "pwm-fan";
+		cooling-levels = <0 35 64 100 150 255>;
+		fan-supply = <&vcc5v0_sys>;
+		pwms = <&pwm1 0 50000 0>;
+		#cooling-cells = <2>;
+	};
+
 	sound {
 		compatible = "simple-audio-card";
 		pinctrl-names = "default";

@@ -591,6 +600,36 @@ &i2s6_8ch {
 	status = "okay";
 };
 
+&package_thermal {
+	polling-delay = <1000>;
+
+	trips {
+		package_warm: package-warm {
+			temperature = <50000>;
+			hysteresis = <2000>;
+			type = "active";
+		};
+
+		package_hot: package-hot {
+			temperature = <60000>;
+			hysteresis = <2000>;
+			type = "active";
+		};
+	};

It should be better to use 55 and 65 oC as the trip thresholds,
because people often report around 50 oC as the observed idle-state
temperature of their RK3588 SoCs, so increasing the first threshold

Were these people using the heatsink accessory on the NanoPC-T6, or were
they using some other board with worse heat dissipation? I recorded the
package temperature on my NanoPC-T6 with the FriendlyELEC heatsink and fan
and even though it's not idle but actually running Home Assistant,
OpenLDAP, PostgreSQL, Prometheus, Grafana and Nginx, the temperature ranges
between 46 and 48°C, and the fan never even spins up.

Then I ran stress-ng and recorded the temperature under CPU load, with this
version of the patch and another version with 55 & 65°C trip points. [1]

I suspect if people are seeing 50°C at idle, they're either using a less
effective heatsink, or in a very warm ambient temperature. When talking
about the NanoPC-T6 fan specifically, we kinda have to assume the
FriendlyELEC heatsink is used, as there's no mounting for the fan without
the heatsink.

to 55 oC should be beneficial by preventing the fan from spinning
when the SoC is actually idle.  The second threshold is usually set
to be 10 oC higher, so it should end up at 65 oC.

I'll send a v3 with 55 and 65°C trip points, but I doubt it makes any
difference to the fan activating while idle; from my testing it seems to
just let the SoC get a bit hotter under heavy load.

[1]: https://gist.github.com/sigmaris/2d5590271cf26da8ec6cfc7ef8e3e8bc

quoted

+	cooling-maps {
+		map0 {
+			trip = <&package_warm>;
+			cooling-device = <&fan THERMAL_NO_LIMIT 1>;
+		};
+
+		map1 {
+			trip = <&package_hot>;
+			cooling-device = <&fan 2 THERMAL_NO_LIMIT>;
+		};
+	};
+};
+
 &pcie2x1l0 {
 	reset-gpios = <&gpio4 RK_PB3 GPIO_ACTIVE_HIGH>;
 	vpcie3v3-supply = <&vcc_3v3_pcie20>;