linux-kernel - Re: About gpio-regulator setting on DT

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Message-ID: <20140129165105.GD22609@sirena.org.uk>
Date:	Wed, 29 Jan 2014 16:51:05 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Ben Dooks <ben.dooks@...ethink.co.uk>
Cc:	Kuninori Morimoto <kuninori.morimoto.gx@...il.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Lee Jones <lee.jones@...aro.org>, Simon <horms@...ge.net.au>,
	Magnus <magnus.damm@...il.com>,
	Linux-SH <linux-sh@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: About gpio-regulator setting on DT

On Wed, Jan 29, 2014 at 04:16:03PM +0000, Ben Dooks wrote:
> On 29/01/14 12:45, Mark Brown wrote:

> >of_get_named_gpio() just looks up the GPIO number, it doesn't request
> >the GPIO.

> I think you've just run in to the same problem that we've found
> with the GPIO regulator code for the vmmcq on the lager where the
> DT probed version is getting 1800mV for MMC whereas the platform
> probed version gets 3300mV for MMC (and thus works better).

> My view is that we should really add an initialisation voltage
> setting to the regulators so that if there is >2 states we can
> select the state it starts in.

The drivers using the regulator should be doing that if the regulator
has variable supplies, the expectation is that trying to provide
something outside of a driver that's actively managing this is just
going to give more opportunity for the system to become fragile.  A
write only driver like the GPIO regulator may want to provide something
but it's not clear to me that this would help for generic regulators.

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