linux-kernel - Re: [PATCH v3 0/6] mfd: axp20x: add AXP221 PMIC support

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Message-ID: <53863D2E.7050008@free-electrons.com>
Date:	Wed, 28 May 2014 21:46:54 +0200
From:	Boris BREZILLON <boris.brezillon@...e-electrons.com>
To:	Mark Brown <broonie@...nel.org>
CC:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Carlo Caione <carlo@...one.org>,
	Shuge <shuge@...winnertech.com>, kevin@...winnertech.com,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	dev@...ux-sunxi.org
Subject: Re: [PATCH v3 0/6] mfd: axp20x: add AXP221 PMIC support


Hello Mark,

On 27/05/2014 21:49, Mark Brown wrote:
> On Tue, May 27, 2014 at 11:38:49AM +0200, Boris BREZILLON wrote:
>
>> I'm still waiting for inputs regarding the ipsout regulator representation:
> If you've got questions you need an answer to urgently it's possibly
> best to highlight them outside of a series like this doing that helps
> make it more obvious.

Noted. I'll take care to send a separate mail next time.

BTW, I don't if you've noticed, but patch 5 of this series implements
helper functions to register several regulators from a regulator_desc
and an of_regulator_match table (as you suggested).

>>  * The ipsout regulator is currently represented as a fixed regulator
>>    providing a 5v output, and this is not exactly the case.
>>    AFAIU (here's is the datasheet traduction if you want to check [1]), the
>>    ipsout output is a multiplexer that choose among vbus (5V), acin (12V
>>    which is then converted to 5V) and the battery power supply (3,5 -> 4,2 V).
>>    This means the output voltage of ipsout vary between 3,5V and 5V.
>>    How can we express this kind of muxer in the regulator framework (is there
>>    already something available ?) ?
>>    Note that the power supply selection is automatic, though we could force
>>    one power supply, but then we loose the ability to unplug one power supply
>>    without impacting the system.
> This sounds like it may as well just be represented as an unregulated
> supply - it's just the system root supply really.  Nothing can rely on
> the voltage anyway as it's going to vary randomly depending on what the
> user does power wise and typically it'd only be used as a supply for
> things that don't care about the specific voltage.

Okay, I'm fine with that.

Thanks.

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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