linux-kernel - Re: [PATCH 2/2] regulator: add mxs regulator driver

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Message-ID: <20141001155733.GA4273@sirena.org.uk>
Date:	Wed, 1 Oct 2014 16:57:33 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Stefan Wahren <stefan.wahren@...e.com>
Cc:	kernel@...gutronix.de, pawel.moll@....com, lgirdwood@...il.com,
	robh+dt@...nel.org, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, linux-kernel@...r.kernel.org,
	shawn.guo@...aro.org, festevam@...il.com, mark.rutland@....com,
	devicetree@...r.kernel.org
Subject: Re: [PATCH 2/2] regulator: add mxs regulator driver

On Wed, Oct 01, 2014 at 03:23:44PM +0200, Stefan Wahren wrote:

> Is it better to let the core handles the ramp delay instead of set_voltage_sel
> with a busy wait?

> I've found that polling DC_OK is only reliable for increasing voltages. So i
> think about defining ramp delay in the regulator description.

It's better to use the notification from the device if it is reliable;
dead reckoning isn't going to work well either for voltage reduction
since the time taken to implement a drop in voltage is more a function
of the loading than anything else, the regulator can't really control
it.  For most DC-DC loads it'll be quick enough though.

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