linux-kernel - Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over

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Message-ID: <CABdtJHukOOMN7zsrAUQYma==N_t+LYmgWLpqJvZZNwg8PBM7dA@mail.gmail.com>
Date:   Mon, 27 Jul 2020 19:04:48 +0200
From:   Jon Nettleton <jon@...id-run.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Rob Herring <robh@...nel.org>,
        Miguel Borges de Freitas <miguelborgesdefreitas@...il.com>,
        a.zummo@...ertech.it, Baruch Siach <baruch@...s.co.il>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for
 battery switch-over

On Mon, Jul 27, 2020 at 6:16 PM Alexandre Belloni
<alexandre.belloni@...tlin.com> wrote:
>
> On 27/07/2020 17:55:50+0200, Jon Nettleton wrote:
> > > So, can we please have that discussion, it is pertinent to this patch.
> > >
> >
> > Thinking about this some more, I believe whether or not an IOCTL
> > interface is in the works or needed is irrelevant.  This patch
> > describes the hardware and how it is designed and the topic of
> > discussion is if we need a simple boolean state, or if we need
> > something that could be used to support dynamic configuration in the
> > future.  I would rather make this decision now rather than keep
> > tacking on boolean config options, or revisit a bunch of device-tree
> > changes.
>
> Something that would describe the hardware is a property telling whether
> the filter is present on VDD, not a property selecting DSM. The driver
> can then chose to avoid standard mode when needed.
>

The filter being present or not is not the singular hardware
requirement for making this determination.  There is no reason to make
this some obtuse argument.  There are two states and you may want one
or the other, or the ability to switch between them.  This is a flag
to tell the driver how the hardware should be configured based on the
board preference.  Let's find a simple consistent way to do this.