linux-kernel - Re: [PATCH] regulator: Lookup unresolved parent supplies before regulators cleanup

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Date:	Mon, 21 Mar 2016 12:37:52 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>,
	Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH] regulator: Lookup unresolved parent supplies before
 regulators cleanup

On Mon, Mar 21, 2016 at 09:13:55AM -0300, Javier Martinez Canillas wrote:
> On 03/21/2016 08:11 AM, Mark Brown wrote:
> > On Sun, Mar 20, 2016 at 11:39:46PM -0300, Javier Martinez Canillas wrote:

> >> This patch makes the unresolved parent supplies to be looked up before the
> >> regulators late cleanup, so those with a child marked as always on will be
> >> enabled regardless if a driver attempted to get the child regulator or not.

> > This doesn't make much sense to me as a fix - it feels like we're doing
> > a fragile hack.  Surely it's better to do this as we register the
> > devices, that way we're also protected against any similar issues with

> Sorry, not sure if I understood correctly. You mean to do it when the
> drivers register the regulators, so at regulator_register() ?

> That's basically what was done before Bjorn's patch but that doesn't
> handle the case of out of order registration when having circular
> dependencies between regulators.

We used to look for the parent at registration time, we didn't look for
the children.  What you're trying to do here is look for the children;
we can do that at registration time.

> > this that might occur after late probe if things are built modular?  Or

> Someone told me once that modules are always a special case :)

That doesn't mean we should actively go out of our way to break them.

> The reason why I did in late_initcall / regulator_init_complete is that
> the problem for me is that unused regulators are disabled on cleanup but
> parents whose childrens are marked as always on should be keep enabled.

> But these are disabled anyways just because the regulator core didn't know
> about that dependency. So doing it before the late cleanup sounded like a
> good solution for me.

Regulators also get disabled if some consumer disables them, that can
happen separately to late_initcall() and often happens during consumer
device probe.

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