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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAFBinCCyEVbc4N7TUEi=sbLFv7Rc-L=y-h8xBuZK446x1oLc2g@mail.gmail.com>
Date:   Wed, 19 Oct 2022 22:40:18 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     neil.armstrong@...aro.org, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: meson: Enable active coling using gpio-fan on
 Odroid N2/N2+

Hi Anand,

On Wed, Oct 19, 2022 at 7:17 PM Anand Moon <linux.amoon@...il.com> 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.


Best regards,
Martin


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