linux-kernel - Re: [PATCH v2] Input: Make ADS7846 independent on regulator

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Message-ID: <20101005225223.GC23315@opensource.wolfsonmicro.com>
Date:	Tue, 5 Oct 2010 15:52:24 -0700
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Linus Walleij <linus.ml.walleij@...il.com>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Igor Grinberg <grinberg@...pulab.co.il>,
	Marek Vasut <marek.vasut@...il.com>,
	linux-arm-kernel@...ts.infradead.org, vapier@...too.org,
	khilman@...prootsystems.com, linux-kernel@...r.kernel.org,
	pavel@....cz, linux-input@...r.kernel.org, eric.y.miao@...il.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH v2] Input: Make ADS7846 independent on regulator

On Wed, Oct 06, 2010 at 12:09:39AM +0200, Linus Walleij wrote:

> This wrapper function will accept non-existing regulators and
> not treat them as errors. Consumers will have to NULL-check their
> regulators.

No, this is actively unhelpful.  If consumers can null check their
regulators then they can just as well do an IS_ERR() check and if we
just eat null pointers like this then the API doesn't degrade gracefully
when it can't implement things - for example, your regulator_set_voltage() 
will report success when it fails to set a voltage which is going to
upset any consumer that thinks it did actually change the current
voltage.

The existing dummy regulator support already does all this in a manner
which is much less invasive for the core.
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