[PATCH v5 03/12] arm64: dts: rockchip: Use a longer PWM period for the fan on Radxa ROCK 5C

FUKAUMI Naoki
2024-12-16T12:39:55Z

The fan on Radxa ROCK 5C is driven via an AO3416 MOSFET, which has a
total switch-on time of 0,6us and a total switch-off time of 6us [1],
meaning that the current PWM period of just 10us is too short for
fine-grained fan speed control. Increase the PWM period to 60us, so
that the switch-on and switch-off time of the MOSFET fall within a
more reasonable ~10% of the full period, thus making lower PWM duty
cycles meaningful.

[1] https://www.aosmd.com/pdfs/datasheet/AO3416.pdf

Fixes: 3ddf5cdb77e6 ("arm64: dts: rockchip: add Radxa ROCK 5C")
Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
---
Changes in v5:
- Reword commit message (Alexey Charkov)
Changes in v4:
- none
Changes in v3:
- none
Changes in v2:
- reword commit message
---
arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts b/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
index 630f026d856c..85589d1a6d3b 100644
--- a/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
@@ -73,7 +73,7 @@ pwm-fan {
#cooling-cells = <2>;
cooling-levels = <0 64 128 192 255>;
fan-supply = <&vcc_5v0>;
- pwms = <&pwm3 0 10000 0>;
+ pwms = <&pwm3 0 60000 0>;
};

pcie2x1l2_3v3: regulator-pcie2x1l2-3v3 {
--
2.43.0