linux-kernel - Re: Doubt about Regulator Framework and VBAT use case

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Message-ID: <20091130104353.GB16608@esdhcp037198.research.nokia.com>
Date:	Mon, 30 Nov 2009 12:43:53 +0200
From:	Eduardo Valentin <eduardo.valentin@...ia.com>
To:	"Valentin Eduardo (Nokia-D/Helsinki)" <eduardo.valentin@...ia.com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	"Hogander Jouni (Nokia-D/Tampere)" <jouni.hogander@...ia.com>,
	"De-Schrijver Peter (Nokia-D/Helsinki)" 
	<Peter.De-Schrijver@...ia.com>,
	"Keski-Saari Juha.1 (EXT-Teleca/Helsinki)" 
	<ext-juha.1.keski-saari@...ia.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Liam Girdwood <lrg@...mlogic.co.uk>
Subject: Re: Doubt about Regulator Framework and VBAT use case

Forgot to add Liam into Cc. Doing it so.


On Mon, Nov 30, 2009 at 11:41:02AM +0100, Valentin Eduardo (Nokia-D/Helsinki) wrote:
> Hello Mark and Liam,
> 
> I'm writing to ask about VBAT use case. What is the expected
> way to use regulator framework in case of rail coming from battery?
> Should it be added to the regulator framework at all?
> 
> In that case, the rail should not be controllable. So I don't see
> any reason to add it to the regulator framework board definitions,
> as we should not be controlling it.
> 
> However, drivers for devices on that rail would require their regulator anyway.
> And I guess the point would be that drivers should not be aware that they are on VBAT
> or any other rail.
> 
> So, what's the correct way to solve this?
> 
> - Should drivers fail nicely if a regulator_get fail? And continue even if one fails.
> - Should drivers disable regfw usage completely in the driver if regulator_get doesn't
> give valid regulator ?
> - or Should a fake fixed regulator be added for vbat so drivers can still get a valid
> regulator with regulator_get.
> 
> The last options seams to be the one that does not require much changes on drivers.
> But it will be adding a regulator that does basically nothing in the system.
> 
> BR,
> 
> -- 
> Eduardo Valentin
> --
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-- 
Eduardo Valentin
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