Date: Mon, 29 Jul 2019 21:49:57 +0200 From: "Filippo Valsorda" <filippo@ml.filippo.io> To: freebsd-arm@freebsd.org Subject: PWM fan control on Helios4 (Marvell ARMADA 388) Message-ID: <5dfec78c-9a41-4e01-8834-ec0178f1ac9d@www.fastmail.com>
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I am running FreeBSD 12.0-GENERIC-350203 on the Helios4, a Marvell ARMADA 388 board. The device tree has two PWM GPIO fans https://github.com/Artox/crochet/blob/4d40896f182ad704e23dd55c31290f5859145483/board/Clearfog/files/armada-388-helios4.dts#L133-L141 but it doesn't look like the OS can see them at all, and they spin at full speed. Here's the full sysctl. https://gist.github.com/FiloSottile/5a44f2fd0bacb44b4120b1f5c6828583 Interestingly, the Linux DTS has different pwms parameters, but I couldn't find documentation on what they are. https://github.com/torvalds/linux/blob/2a11c76e5301dddefcb618dac04f74e6314df6bc/arch/arm/boot/dts/armada-388-helios4.dts#L123 The Helios4 PWM circuits seem very well documented, at least. https://wiki.kobol.io/pwm/ I would like to be able to slow the fans down. Runtime changes or adaptive behavior are a plus, but I'd be also happy with setting them at a fixed duty cycle. What docs should I look at? Has anyone tried this? What are my options, short of a hardware controller? Thank you, Filippo (Please keep me CC'd.)
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