linux-kernel - Re: [PATCH v15 1/8] dt-bindings: mfd: Initial commit of silergy,sy7636a.yaml

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Date:   Thu, 2 Dec 2021 21:45:39 +1000
From:   Alistair Francis <alistair23@...il.com>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     Alistair Francis <alistair@...stair23.me>,
        Lee Jones <lee.jones@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>, lgirdwood@...il.com,
        Rob Herring <robh+dt@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        rui.zhang@...el.com, devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-hwmon@...r.kernel.org, amitk@...nel.org,
        linux-pm@...r.kernel.org, dl-linux-imx <linux-imx@....com>,
        Shawn Guo <shawnguo@...nel.org>, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v15 1/8] dt-bindings: mfd: Initial commit of silergy,sy7636a.yaml

On Thu, Dec 2, 2021 at 8:36 AM Andreas Kemnade <andreas@...nade.info> wrote:
>
> Hi,
>
> [...]
> > > > This is a vcom in the sense of voltage for compensation. We just
> > > > currently don't support setting the vcom.
> > > >
> > > > I had a look at the Kobo code and this is similar to
> > > > https://github.com/akemnade/linux/blob/kobo/epdc-pmic-5.15/drivers/regulator/sy7636-regulator.c#L614
> > > >
> > > > So I think that vcom is still the appropriate name for this.
> > > >
> > > seems that you did not get me. If I understand the code behind it
> > > correctly, it turns on all power rails (the +-15V stuff, VEE and so on)
> > > with the defined delays, not just vcom because it sets
> > > SY7636A_OPERATION_MODE_CRL_ONOFF. Controlling VCOM separately is possible
> > > by using SY7636A_OPERATION_MODE_CRL_VCOMCTL in combintion with a
> > > vcom_en gpio.
> > >
> > > I do not see a reason to turn on vcom only without the other higher
> > > voltage rails, so the behaviour is not necessarily wrong but if I read
> > > the binding documentation I would expect that just vcom is turned on.
> > > That is the mismatch I am talking about.
> >
> > Ah! Ok I understand. I'll rename it to vdd then.
> >
> Most important is IMHO some human-readable description in the bindings
> document.

That is what I ended up going with instead.

Alistair

>
> I am also just wondering whether this kind of logical
> regulator which turns on several other regulators is actually accepted
> or just slipped through review. I have no strong opinion here. I just
> want to be able to clean up the tps65185 driver in the same way and not
> having two similar pmics with different bindings and then a mess at the
> consumer side.
>
> Regards,
> Andreas