linux-kernel - Re: [PATCH] PCAP regulator driver (for 2.6.32).

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Date:	Fri, 26 Jun 2009 09:26:32 -0300
From:	Daniel Ribeiro <drwyrm@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Liam Girdwood <lrg@...mlogic.co.uk>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	openezx-devel <openezx-devel@...ts.openezx.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	David Brownell <dbrownell@...rs.sourceforge.net>
Subject: Re: [PATCH] PCAP regulator driver (for 2.6.32).

Em Sex, 2009-06-26 às 11:55 +0100, Mark Brown escreveu:
> On Fri, Jun 26, 2009 at 03:04:23AM -0300, Daniel Ribeiro wrote:
> > So, the regulator is enabled at boot, but it can't be disabled because
> > use_count is 0. This is the same issue as twl4030-mmc, but instead of a
> > enable/disable pair on pxamci.c i opted to disable it at pcap's
> 
> At the minute you need to use the enable/disable pair since (as we've
> previously discussed) the API needs to support regulators which are
> shared between multiple users (potentially including multiple users from
> the same consumer).

> You need to either do that or add an API allowing consumers to claim a
> regulator for exclusive use.  If the regulator is claimed for exclusive
> use then other consumers wouldn't be able to access it and there would
> be no issue with interfering with other users.

I'm not proposing an API for exclusive use. Allowing the enable bit to
be turn off case use_count is 0 shouldn't break regulator sharing for
other consumers, as far as the regulator framework is concerned there
are no other consumers.

What about increasing use_count at regulator_get() if the regulator is
already on and use_count == 0? If a consumer requests a regulator that
was previously ON, then there is no reason for it to enable/disable it.
If it is requested, and its already ON, then the regulator framework can
assume it is already being used.

If the above is not possible, then regulator_is_enabled() doesn't match
regulator_enable()/regulator_disable() pair. Maybe the API should make
this clear?

-- 
Daniel Ribeiro

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