linux-kernel - Re: [PATCH] leds: Add LED class driver for regulator driven LEDs.

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Message-ID: <20091204124505.GA3320@sirena.org.uk>
Date:	Fri, 4 Dec 2009 12:45:05 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Antonio Ospite <ospite@...denti.unina.it>
Cc:	Richard Purdie <rpurdie@...ys.net>,
	Liam Girdwood <lrg@...mlogic.co.uk>,
	Daniel Ribeiro <drwyrm@...il.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	openezx-devel@...ts.openezx.org
Subject: Re: [PATCH] leds: Add LED class driver for regulator driven LEDs.

On Fri, Dec 04, 2009 at 01:39:43PM +0100, Antonio Ospite wrote:
> Mark Brown <broonie@...nsource.wolfsonmicro.com> wrote:

> > You almost certainly want regulator_get_exclusive() here; this driver
> > can't function properly if something else is using the regulator and
> > holding the LED on or off without it.  You'll also want to check the
> > status of the LED on startup and update your internal status to match
> > that.

> When you refer to "the status of the LED on startup" do you mean a
> initial brightness value passed via leds-regulator platform data, or the
> initial status or the regulator itself?

The hardware state at startup; I would imagine that you'd want to make
setting the initial state via platform data optional in order to enable
a smooth handover from bootloader to Linux where the state may depend on
the runtime state (eg, charging indication).
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