linux-kernel - Re: [PATCH] ARM: dts: sun8i-h2-plus-bananapi-m2-zero: add gpio-poweroff to DT

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Message-ID: <20201124132105.oai6gejdvdsnbzyx@gilmour>
Date:   Tue, 24 Nov 2020 14:21:05 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Samuel Holland <samuel@...lland.org>,
        Michael Klein <michael@...sekall.de>,
        Rob Herring <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: dts: sun8i-h2-plus-bananapi-m2-zero: add
 gpio-poweroff to DT

On Tue, Nov 24, 2020 at 12:41:37PM +0800, Chen-Yu Tsai wrote:
> On Tue, Nov 24, 2020 at 12:14 PM Samuel Holland <samuel@...lland.org> wrote:
> >
> > On 11/23/20 10:10 AM, Michael Klein wrote:
> > > Add gpio-poweroff node to allow the board to power itself off after
> > > shutdown by disabling the SYSTEM and CPUX regulators (U5 resp. U6).
> > > The RST button can be used to restart the board.
> >
> > The PSCI client will override this driver once the PSCI implementation
> > is upgraded to v0.2 or newer functions. So having this around should
> > cause no compatibility issues (although it would print an error in dmesg
> > at that point). This seems like a reasonable thing to do for the other
> > H2+/H3 boards that use a similar regulator layout.
> 
> I wonder if this (gpio-poweroff) works if those regulators are also in the DT?

It's probably not going to probe at all, since both would claim the
exclusive usage of the GPIO?

I guess we should model this properly using the regulator framework, and
regulator_force_disable allows to bypass any usage count

Maxime

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