linux-kernel - Re: [PATCH] regulator: arizona-ldo1: Add ramp time for HI

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Message-ID: <20150324170554.GP17265@sirena.org.uk>
Date:	Tue, 24 Mar 2015 10:05:54 -0700
From:	Mark Brown <broonie@...nel.org>
To:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:	lgirdwood@...il.com, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH] regulator: arizona-ldo1: Add ramp time for HI_PWR

On Tue, Mar 24, 2015 at 04:40:50PM +0000, Charles Keepax wrote:
> On Tue, Mar 24, 2015 at 09:06:09AM -0700, Mark Brown wrote:

> > So changes to move to the top voltage always take constant time while
> > all other voltage changes are instantaneous?  That doesn't seem right.
> > I'd expect something more like a calculation based on some number of
> > miliseconds per milivolt.

> Its more just that this is the only case that we really care
> about. The reg only ever gets used at 1.2V and 1.8V, and the
> only case where there is a problem is if we ask for 1.8V and
> we don't have it yet.

> I don't think we really have the data to give for other cases. I
> could expand the comment perhaps? Or TBH it is fast enough it is
> unlikely to ever be a problem in practice so we could just drop
> the patch.

You'll probably find that the ramp is pretty much linear so just
changing to something that multiplies out to the expected value will be
good enough.  I'd rather not have bad examples that other drivers might
copy.

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