linux-kernel - Re: [PATCH/RFC 4/5] regulator: bd9571mwv: Add support for backup mode

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Message-ID: <20171024083432.j3xqepkvprbvg2p4@sirena.org.uk>
Date:   Tue, 24 Oct 2017 10:34:32 +0200
From:   Mark Brown <broonie@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH/RFC 4/5] regulator: bd9571mwv: Add support for backup mode

On Wed, Oct 18, 2017 at 01:28:30PM +0200, Geert Uytterhoeven wrote:
> On Wed, Oct 18, 2017 at 1:24 PM, Mark Brown <broonie@...nel.org> wrote:

> >> Hence you cannot enable wakeup mode while suspending, as the proper
> >> system suspend/resume procedure is:
> >>   1. Enable backup mode in the PMIC,
> >>   2. Switch ACC off (no-op as backup mode has been enabled),
> >>   3. Suspend to RAM (PSCI suspend) => system suspends,
> >>   4. Switch ACC on => system wakes up.
> >> If you would combine steps 1 and 3, you can no longer do step 2 in between.

> >> Yes, it's complicated :-(

> > I'm confused, I thought this was a physical switch but that's talking
> > about this as something software controlled (at least in step 2)?

> The ACC switch is a physical switch.
> Steps 1 and 3 are performed by software running on the board's SoC.
> Steps 2 and 4 are performed by the external user (human or remote board
> farm control hookup).

That's horrible.  There's still the question about potentially using the
existing wakeup file to manage if the device is a wakeup source but
otherwise I guess the only other thing that'd make sense would be just
having a property in the DT.

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