linux-kernel - Re: [PATCH] regulator: palmas: Fix calculating selector in palmas_map_voltage

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Message-ID: <20120718100615.GD22739@opensource.wolfsonmicro.com>
Date:	Wed, 18 Jul 2012 11:06:15 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Graeme Gregory <gg@...mlogic.co.uk>
Cc:	Axel Lin <axel.lin@...il.com>, linux-kernel@...r.kernel.org,
	Liam Girdwood <lrg@...com>
Subject: Re: [PATCH] regulator: palmas: Fix calculating selector in
 palmas_map_voltage_ldo

On Wed, Jul 18, 2012 at 08:55:30AM +0100, Graeme Gregory wrote:
> On 18/07/12 04:30, Axel Lin wrote:
> > This patch fixes below issues when choosing selector:

> > 1. Current code returns negative selector if min_uV < 900000 which is wrong.
> >    For example, it is possible to satisfy the request with selector = 1 if
> >    the requested min_uV is 850000.

> Isnt this defending against bugs in the regulator core? I am normally
> against repeating the same checks at multiple levels in a stack.

This isn't a bug in the core, a negative selector is an error code (and
in general whatever selector is returned by the driver ought to agree
with selectors the driver actually supports).  It's probably at least a
questionable decision in the machine constraints to allow a request for
less than the regulator can deliver to get through though.

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