linux-kernel - Re: [PATCH] regulator: core: Keep boot

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Message-ID: <20120423101804.GA8318@opensource.wolfsonmicro.com>
Date:	Mon, 23 Apr 2012 11:18:05 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Ulf Hansson <ulf.hansson@...ricsson.com>
Cc:	Liam Girdwood <lrg@...mlogic.co.uk>, linux-kernel@...r.kernel.org,
	Mattias Wallin <mattias.wallin@...ricsson.com>,
	Jonas Aberg <jonas.aberg@...ricsson.com>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH] regulator: core: Keep boot_on regulators powered during
 init

On Mon, Apr 23, 2012 at 11:37:53AM +0200, Ulf Hansson wrote:

> Regulators which has boot_on constraints set, will now remain
> powered after regulator_init_complete is done.

This would be a bug.  All boot_on means is that the regulator was turned
on during boot, the regulator is free to vary after that.

> In this case we leave the enable->disable operation to be
> handled by the regulator consumer instead.

Which would be a bug if the consumer wasn't the thing that took the
reference to the regulator in the first place.  Remember, regulators can
be shared so the consumer can't disable a regulator it didn't enable in
the first place (unless it used regulator_get_exclusive() but the use
cases for that are a little suspicious so it'd be worth taking a careful
look before using it).  A consumer can't tell if the regulator was left
enabled by the firmware on boot or if it has been enabled by another
consumer.

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