Date: Thu, 31 Dec 2015 21:40:07 +0000
From: Mark Brown <broonie@kernel.org>
To: Paul Kocialkowski <contact@paulk.fr>
Cc: Milo Kim <milo.kim@ti.com>, linux-kernel@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>,
        Russell King <linux@arm.linux.org.uk>,
        =?iso-8859-1?Q?Beno=EEt?= Cousson <bcousson@baylibre.com>,
        Tony Lindgren <tony@atomide.com>, Liam Girdwood <lgirdwood@gmail.com>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-omap@vger.kernel.org
Message-ID: <20151231214007.GC16023@sirena.org.uk>
References: <1450868319-20513-5-git-send-email-contact@paulk.fr>
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 <5681D7A8.2030101@ti.com>
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Subject: Re: [PATCH 4/6] regulator: lp872x: Add enable GPIO pin support
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On Wed, Dec 30, 2015 at 07:37:19PM +0100, Paul Kocialkowski wrote:
> Le mercredi 30 d=E9cembre 2015 =E0 16:33 +0000, Mark Brown a =E9crit :
> > On Wed, Dec 30, 2015 at 09:35:21AM +0100, Paul Kocialkowski wrote:

> > > In my opinion, it would be more elegant to adapt the core regulator
> > > framework to first enable the GPIO and then call the regulator enable
> > > ops callback instead of handling the GPIO in the driver.

> > Why would we want to actively manage both things at runtime?  It's more
> > work, what do we gain from it?

> Well, I figured that it would be best to disable the EN pin when we're
> not using any of the regulators, since that allows the chip to enter
> standby mode (and thus consume less power).

This doesn't sound like it's anything to do with the regulators, that's
a chip wide power management function which should be implemented via
runtime PM if there's any value in implementing it at all (if the device
is a primary PMIC normally this would be handled by the CPU core when it
enters low power state without any software).  It's not something we
should be considering on a per regulator basis since it's at the chip
level and on a per regulator basis it's not doing anything useful for
the reasons above.

> It also doesn't hurt regulators that only use a GPIO for enable.

It causes problems for any device with an optional GPIO,  it means that
we end up mantaining both GPIO and register which as I've said a couple
of times now defeats the point of having the GPIO.

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