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

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Message-ID: <20150324171925.GL23705@opensource.wolfsonmicro.com>
Date:	Tue, 24 Mar 2015 17:19:25 +0000
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	Mark Brown <broonie@...nel.org>
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 10:05:54AM -0700, Mark Brown wrote:
> 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.

Cool, I will respin.

Thanks,
Charles
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