linux-kernel - Re: [PATCH v3 06/12] power: pwrseq: simple: Add support for regulator and generic property

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Date:	Wed, 8 Jun 2016 14:03:33 -0500
From:	Rob Herring <robh@...nel.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	hzpeterchen@...il.com, Ulf Hansson <ulf.hansson@...aro.org>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Javier Martinez Canillas <javier@....samsung.com>,
	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
	linux-pm@...r.kernel.or, Alan Stern <stern@...land.harvard.edu>,
	linux-usb@...r.kernel.org, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Kukjin Kim <kgene@...nel.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v3 06/12] power: pwrseq: simple: Add support for
 regulator and generic property

On Tue, Jun 07, 2016 at 11:29:02AM +0200, Krzysztof Kozlowski wrote:
> On 06/03/2016 04:02 AM, Rob Herring wrote:
> >>  Optional properties:
> >>  - reset-gpios : contains a list of GPIO specifiers. The reset GPIOs are asserted
> >> @@ -16,6 +22,7 @@ Optional properties:
> >>    See ../clocks/clock-bindings.txt for details.
> >>  - clock-names : Must include the following entry:
> >>    "ext_clock" (External clock provided to the card).
> >> +- ext-supply : External regulator supply
> > 
> > What happens when there are 2 supplies?
> > 
> > I'd prefer the name not be genericish and use the real supply names. 
> > Then the power seq code should just turn on all supplies it finds. If 
> > the order or timing to turn on matters, then sorry, no generic sequence.
> 
> I think the generic part for regulators might be a problem. Regulator
> API requires a name for the supply... it cannot get "something" or
> "everything".

That's the downside of variable property names...

> The driver could attach itself to any kind of node (where power-sequence
> property exists) so the supply name depends on the bindings of device
> (not bindings of power sequence driver).
> 
> The power sequence driver could however iterate over child properties
> and get the names of all supplies. It is a little bit ugly...

Yes. Like this, right?

for_each_property_of_node(np, pp) {
	if (!strstr(pp->name, "-supply"))
		continue;
	// found supply
}

The uglyness can always be improved with a function to do this parsing.

Rob