linux-kernel - Re: [PATCH v2 11/14] regulator: s2mps11: Add opmode for S2MPS14 regulators

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Message-id: <1392624454.3755.12.camel@AMDC1943>
Date:	Mon, 17 Feb 2014 09:07:34 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Yadwinder Singh Brar <yadi.brar01@...il.com>,
	Sangbeom Kim <sbkim73@...sung.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Tomasz Figa <t.figa@...sung.com>
Subject: Re: [PATCH v2 11/14] regulator: s2mps11: Add opmode for S2MPS14
 regulators

On Fri, 2014-02-14 at 21:05 +0000, Mark Brown wrote:
> On Fri, Feb 14, 2014 at 02:05:56PM +0100, Krzysztof Kozlowski wrote:
> > On Thu, 2014-02-13 at 17:46 +0530, Yadwinder Singh Brar wrote:
> 
> >  - low-power mode;
> >  - low-power mode controlled by PWREN;
> > Although not all are present for each regulator.
> 
> What exactly is low power mode and how does it interact with the enable?
> The name suggests it's a more efficient mode for use with low current
> drain, is that right?

Yes, it is (i.e. ground current on battery load typically reduced from
8mA to 1.5mA). In this mode for Buck5 and LDO-s the regulator is enabled
but output current is limited to 5 mA.

> 
> > A generic solution for operating mode of regulators (not only s2mps11
> > and s5m8767) could cover all of these above or just a subset, for
> > example regulator bindings could look like:
> >  - regulator-mode-suspend; /* PWR controls: on/off or low-power mode */
> >  - regulator-mode-low-power; /* Low power mode */
> 
> Those properties have awfully generic names and part of what I was
> wondering above is if the low power mode maps onto the idle or standby
> modes that the API defines?  We don't cover those in the bindings yet
> since they are unfortunately fuzzy but perhaps we need to do so.

The low power maps to REGULATOR_MODE_IDLE or REGULATOR_MODE_STANDBY
(depending on the understanding of "more efficient" and "most efficient"
for light loads). However the suspend mode of S5M8767/S2MPS14 is more
like automatic regulator disable by SoC.

Best regards,
Krzysztof


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