linux-kernel - Re: [PATCH 01/16] PM / OPP: Add 'supply-names' binding

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Message-ID: <20151016060227.GS19018@linux>
Date:	Fri, 16 Oct 2015 11:32:27 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Rob Herring <robh@...nel.org>, Rafael Wysocki <rjw@...ysocki.net>,
	nm@...com, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, rob.herring@...aro.org,
	lee.jones@...aro.org, Mark Brown <broonie@...nel.org>,
	devicetree@...r.kernel.org,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	open list <linux-kernel@...r.kernel.org>,
	Mark Rutland <mark.rutland@....com>,
	Pawel Moll <pawel.moll@....com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 01/16] PM / OPP: Add 'supply-names' binding

On 15-10-15, 17:22, Stephen Boyd wrote:
> I'm lost why we need this property at all. What happened to using
> 
>  opp-microvolt-0 = <1 2 3>;
>  opp-microvolt-1 = <1>;
>  opp-microvolt-2 = <3 4 5>;
>  etc.

Perhaps you are confusing this with the bindings we came up for
picking right voltage levels based on the cuts/version of the hardware
we are running on. The problem that Lee Jones mentioned and that can
be used in your case as well.

> That seems to avoid any problem with 3 vs. 1 element properties
> combined into one large array.

That's not the problem I was trying to solve here.

> Having supply-names seems too
> brittle and would tie us to a particular OPP user's decision to
> call supplies by some name.

No. The name has to match the <name>-supply property present in the
device's node, that's why we need this property :)

> Also, I've seen devices that are split across two power domains.
> These devices aren't CPUs, but they are other devices including
> L2 caches. So we're going to need either multiple regulator
> support or multiple "power domain at a particular performance
> levels" support somehow.

Right, that's a good example of why we need multi-regulator support :)

-- 
viresh
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