linux-kernel - Re: [PATCH v2 2/2] NFC: nxp-nci: Add pad supply voltage pvdd-supply

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Message-ID: <a3d2dd4f-38ce-40ca-9085-893f808f817b@sirena.org.uk>
Date:   Fri, 9 Jun 2023 20:34:01 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Raymond Hackley <raymondhackley@...tonmail.com>,
        davem@...emloft.net, devicetree@...r.kernel.org,
        edumazet@...gle.com, jk@...econstruct.com.au, kuba@...nel.org,
        lgirdwood@...il.com, linux-kernel@...r.kernel.org,
        michael@...le.cc, netdev@...r.kernel.org, pabeni@...hat.com,
        robh+dt@...nel.org, u.kleine-koenig@...gutronix.de
Subject: Re: [PATCH v2 2/2] NFC: nxp-nci: Add pad supply voltage pvdd-supply

On Fri, Jun 09, 2023 at 09:29:51PM +0200, Krzysztof Kozlowski wrote:
> On 09/06/2023 19:40, Raymond Hackley wrote:
> > On Friday, June 9th, 2023 at 3:46 PM, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:

> > Second condition regulator_is_enabled(pvdd) is to make sure that pvdd is
> > disabled with balance.

> So you have buggy code and to hide the bug you add checks? No, make the
> code correct so the check is not needed.

Specifically your driver should only ever call regulator_disable() to
balance out regulator_enable() calls it made itself and it should know
how many of those it has done.  regulator_is_enabled() should only ever
be used during probe if for some reason it is important to figure out if
the device is already powered for startup, this should be very unusual.
If something else enabled the regualtor then whatever did that needs to
undo those enables, not another driver.

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