linux-kernel - Re: [PATCH 1/3] regulator: core: fix boot-on regulators use

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Date:   Tue, 8 Oct 2019 17:23:33 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     Doug Anderson <dianders@...omium.org>,
        Chunyan Zhang <zhang.chunyan@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        ckeepax@...nsource.cirrus.com, LKML <linux-kernel@...r.kernel.org>,
        Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH 1/3] regulator: core: fix boot-on regulators use_count
 usage

On Tue, Oct 08, 2019 at 06:16:40PM +0200, Marco Felsch wrote:
> On 19-10-08 16:42, Mark Brown wrote:

> > If this is a GPIO regulator then the Linux APIs mean you can't read the
> > status back so it's one of the regulators for which this property was
> > invented.  This is a real limitation of the Linux APIs, with most
> > hardware you can actually read the status back so we shouldn't need
> > this.

> I know and I followed the discussion between you and Doug. But it
> is a valid use-case to have a external gpio-enabled regualtor connected
> to a panel. If I don't mark the regulator as 'regualtor-boot-on' and use
> the fixed.c driver (IMHO this is correct), the regulator gets disabled
> during probe. So I will have a panel off/ panel on sequence during boot.

Right, this is why I am saying that this is one of the regulators for
which this property was defined and where you should be using it.

> To avoid this I set the 'regualtor-boot-on' property but then I can't
> disable the panel during suspend..

As you'll have seen from the discussion that's a bug, nothing should be
taking a reference to the regulator outside of explicit enable calls.

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