linux-kernel - Re: [PATCH V4 2/2] regulator: mt6323: Add support for MT6323 regulator

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Message-ID: <1454069479.10861.30.camel@mtksdaap41>
Date:	Fri, 29 Jan 2016 20:11:19 +0800
From:	menghui lin <menghui.lin@...iatek.com>
To:	Mark Brown <broonie@...nel.org>
CC:	John Crispin <blogic@...nwrt.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	HenryC Chen (陳建豪) 
	<HenryC.Chen@...iatek.com>, <linux-kernel@...r.kernel.org>,
	<linux-mediatek@...ts.infradead.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Chen Zhong <chen.zhong@...iatek.com>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V4 2/2] regulator: mt6323: Add support for MT6323
 regulator

On Fri, 2016-01-29 at 12:27 +0100, Mark Brown wrote:
> On Fri, Jan 29, 2016 at 05:52:14PM +0800, menghui lin wrote:
> > On Fri, 2016-01-29 at 00:13 +0100, Mark Brown wrote:
> 
> > > I'm not convinced this binding makes sense, how would a user of the API
> > > (currently there are none in tree) know what the modes mean?  It's a bit
> > > different when the user is supplying configuration for a specific
> > > regulator but this needs to be something that can be used by consumers.
> 
> > > What are you actually trying to do with this?
> 
> > In this patch, we want to support both normal/standby modes for mt6323
> > regulators due to mt6323 regulators support low power mode which
> > provides better power efficiency for standby case.
> 
> > We expect user of mt6323 regulators could dynamically change power mode
> > by regulator_set_mode(). -EINVAL is returned if the given mode is not
> > supported.
> 
> > The regulator_set_mode() API looks very straightforward and possible
> > modes are already defined in consumer.h. It looks like we don't have to
> > list possible modes for mt6323 additionally in binding document.
> 
> None of this is answering my question - I know what the current API is,
> describing it doesn't tell me about actual users or how they are able to
> sensibly use the interface.  Bear in mind that the definitions of the
> various modes are all relative and what one device thinks is high usage
> may be low usage for another device.

Assuming valid_modes_mask and initial_mode are specified, a possible
way to modify regulator_set_mode() is to allow mode change only if the
regulator is controlled exclusively by a certain consumer or the
requested mode provides stronger power capability than current mode.
Here I assume that power capability fast > normal > idle > standby.