linux-kernel - Re: [PATCH 1/6] regulator: core: Allow simultaneous use of enable op and GPIO

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Message-ID: <20160622103432.GJ28202@sirena.org.uk>
Date:	Wed, 22 Jun 2016 11:34:32 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Alexandre Courbot <acourbot@...dia.com>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	gnurou@...il.com
Subject: Re: [PATCH 1/6] regulator: core: Allow simultaneous use of enable op
 and GPIO

On Wed, Jun 22, 2016 at 05:25:53PM +0900, Alexandre Courbot wrote:
> The current regulator enable/disable mechanism does not call the driver
> enable/disable op if an enable GPIO is set. It may be desirable to use
> both mechanisms though, e.g. in the case of a PWM regulator that also
> has an enable GPIO.
> 
> _regulator_is_enabled() is also updated in order to take both enable
> conditions into account.

This is going to break or at least reduce the performance of a lot of
users - it is very common for regulators to have configurable support
for a GPIO enable in addition to a register enable with the GPIO enable
replacing a register enable for improved performance.  If you have some
strange device that requires GPIO and other operations the driver should
handle that, if nothing else it's likely that there are sequencing
requirements between the two which we are probably not going to get
right for everyone in the core.

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