Re: [PATCH] arm64: dts: meson: Enable active coling using gpio-fan on Odroid N2/N2+

[neil . armstrong]

On 19/10/2022 22:40, Martin Blumenstingl wrote:
> Hi Anand,
>
> On Wed, Oct 19, 2022 at 7:17 PM Anand Moon <linux.amoon@xxxxxxxxx> wrote:
> [...]
> > > > +&pwm_AO_ab {
> > >
> > > &pwm_AO_cd not _ab
> > No it has a conflict with CPU_B (vddcpu_b) PWM
> Uh, you're right. That's probably why the Hardkernel team uses a
> software based PWM implementation: [0]
> In hindsight they should have used a different pad either for VDDCPU_B
> or the fan.
>
> I think the most pragmatic approach (since the "GPIO PWM" driver is
> not upstream and I don't know if something like that would be accepted
> upstream) is to use a GPIO based fan as you did in your initial patch.
> Not sure what others think though.

Indeed I recall them using a SW pwm.

Yes it's perfectly ok to use a gpio-fan.

Anand, please fixup the ddr-active name and send a v2.

Thanks,
Neil

> Best regards,
> Martin
>
>
> [0] https://github.com/hardkernel/linux/blob/c109dec94e7e819554830acfac4b6ed96e230179/arch/arm64/boot/dts/amlogic/meson64_odroidn2.dtsi#L356-L359