linux-kernel - Re: [PATCH v2 2/2] dt-bindings: add devicetree bindings for st-pwm regulator

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Message-ID: <20140918222230.GG7960@sirena.org.uk>
Date:	Thu, 18 Sep 2014 15:22:30 -0700
From:	Mark Brown <broonie@...nel.org>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Chris Zhong <zyw@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	Tao Huang <huangtao@...k-chips.com>,
	Eddie Cai <cf@...k-chips.com>,
	zhangqing <zhangqing@...k-chips.com>,
	Lee Jones <lee.jones@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] dt-bindings: add devicetree bindings for st-pwm
 regulator

On Thu, Sep 18, 2014 at 02:27:59PM -0700, Doug Anderson wrote:
> On Thu, Sep 18, 2014 at 12:31 AM, Chris Zhong <zyw@...k-chips.com> wrote:

> I would be tempted to say that you should add a few required properties:

> * regulator-boot-on
> * regulator-always-on
> * regulator-initial-microvolts

> From my understanding of how PWM-based regulators work there is no way
> to "disable" them.  If you drive them low then they get their biggest
> voltage.  If you drive them high then they get their smallest voltage.
> If you make them floating then it's equivalent to 50% duty cycle
> (right?)

No, if there is no disable operation then there is no point in
specifying any properties to do with enabling and disabling as they
won't do anything.  This is only relevant if the operation is there.

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