linux-kernel - Re: [PATCH] regulator: Use bitfield values for range selectors

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Message-ID: <CAGXv+5EtdhkMq916LLOfpz8ok_xump5tv+oeNBvPq-_3-93oqQ@mail.gmail.com>
Date:   Mon, 12 Jun 2023 11:39:18 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     David Laight <David.Laight@...lab.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Cristian Ciocaltea <cristian.ciocaltea@...il.com>,
        Matti Vaittinen <mazziesaccount@...il.com>,
        "linux-actions@...ts.infradead.org" 
        <linux-actions@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] regulator: Use bitfield values for range selectors

On Sun, Jun 11, 2023 at 1:10 AM David Laight <David.Laight@...lab.com> wrote:
>
> From: Chen-Yu Tsai
> > Sent: 08 June 2023 08:57
> >
> > Right now the regulator helpers expect raw register values for the range
> > selectors. This is different from the voltage selectors, which are
> > normalized as bitfield values. This leads to a bit of confusion. Also,
> > raw values are harder to copy from datasheets or match up with them,
> > as datasheets will typically have bitfield values.
> >
> > Make the helpers expect bitfield values, and convert existing users.
> > Include bitops.h explicitly for ffs(), and reorder the header include
> > statements. While at it, also replace module.h with export.h, since the
> > only use is EXPORT_SYMBOL_GPL.
> >
> ...
> >  static const unsigned int atc260x_ldo_voltage_range_sel[] = {
> > -     0x0, 0x20,
> > +     0x0, 0x1,
> >  };
>
> Is there any way the change can be done so that un-edited
> modules fail to compile?
> Otherwise the whole thing is an accident waiting to happen.

I think we could change the field name in the regulator description?
But unsuspecting end users / developers might just edit the name and not
see that the scheme has changed.

Or we could add a sanity check at runtime that checks the values during
regulator registration. How does that sound?

Mark, is this something you'd like?


ChenYu