linux-kernel - Re: [PATCH RFC] regulator: core: fix handling negative voltages e.g. in EPD PMICs

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Message-ID: <20200224123122.GH6215@sirena.org.uk>
Date:   Mon, 24 Feb 2020 12:31:22 +0000
From:   Mark Brown <broonie@...nel.org>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Andreas Kemnade <andreas@...nade.info>, j.neuschaefer@....net,
        contact@...lk.fr, GNUtoo@...erdimension.org, josua.mayer@....eu,
        lgirdwood@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] regulator: core: fix handling negative voltages e.g.
 in EPD PMICs

On Mon, Feb 24, 2020 at 01:22:21PM +0100, H. Nikolaus Schaller wrote:
> > Am 24.02.2020 um 13:05 schrieb Mark Brown <broonie@...nel.org>:

> > This is what'd be needed, your approach here is a bit of a hack and
> > leaves some values unrepresentable if they overlap with errnos which
> > obviously has issues if someone has a need for those values.

> Negative ERRNOs have BIT(31) set.

This code is working with the numberic representation, not with the
bitwise representation - it's using -MAX_ERRNO.  

> But then it seems to be a little inconsistent that the voltage
> parameters of regulator_set_voltage_unlocked() are signed integers
> and not unsigned.

> So shouldn't that be protected against attempting to set negative voltages?

Or just convert it to unsigned, I don't recall there being any
particular reason why it's signed.

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