On Fri, Aug 13, 2021 at 10:54 AM Daniel Lezcano
[off-list ref] wrote:

Hi Robin,


On 13/08/2021 15:51, Robin Murphy wrote:

quoted

On 2021-08-13 13:59, Daniel Lezcano wrote:

quoted

On 30/07/2021 17:17, Peter Geis wrote:

quoted

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 <redacted>

[ ... ]

quoted

quoted

quoted

  +&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.

That's the same issue I had on the rockpro64.

Thanks for your answer.

What would be the governor for this setup ?

The default governor when using arm64_defconfig is step_wise.

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