linux-kernel - Re: [PATCH] regulator: Ensure voltages are within the allowed range

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Message-ID: <20141112114505.GE3815@sirena.org.uk>
Date:	Wed, 12 Nov 2014 11:45:05 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Thierry Reding <thierry.reding@...il.com>
Cc:	Allen Martin <amartin@...dia.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: Ensure voltages are within the allowed range

On Wed, Nov 12, 2014 at 11:12:05AM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@...dia.com>
> 
> Unless a regulator has a fixed output voltage the core will not attempt
> to modify the output voltage. This can cause a situation where a driver
> enables the regulator but the currently configured voltage is outside
> the valid range.
> 
> Fix this by constraining the current voltage to the allowed range upon
> regulator registration.

I've thought about doing this before but it's tricky as if there is a
voltage range it's possible something needs it at the high rather than
low end of the range and will get upset if the voltage gets lowered.
Setting the top voltage also has risks (though less bad when constraints
are sane) and requires working out what that is which we'd need to write
the machinery to do.

This is all especially likely to break given the depressing desire
everyone seems to have to put the maximum possible voltage range for
their regulators in constraints regardless of what's actually sensible
for their board design.

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