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

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Message-ID: <20190927084710.mt42454vsrjm3yh3@pengutronix.de>
Date:   Fri, 27 Sep 2019 10:47:10 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Mark Brown <broonie@...nel.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

Hi Doug, Mark,

sorry for the delay..

On 19-09-26 12:44, Doug Anderson wrote:
> Hi,
> 
> On Tue, Sep 24, 2019 at 11:28 AM Mark Brown <broonie@...nel.org> wrote:
> > On Mon, Sep 23, 2019 at 03:40:09PM -0700, Doug Anderson wrote:
> > > On Mon, Sep 23, 2019 at 11:49 AM Mark Brown <broonie@...nel.org> wrote:
> > > > On Mon, Sep 23, 2019 at 11:36:11AM -0700, Doug Anderson wrote:
> >
> > > > > 1. Would it be valid to say that it's always incorrect to set this
> > > > > property if there is a way to read the status back from the regulator?
> >
> > > > As originally intended, yes.  I'm now not 100% sure that it won't
> > > > break any existing systems though :/
> >
> > > Should I change the bindings doc to say that?
> >
> > Sure.
> 
> Sent ("regulator: Document "regulator-boot-on" binding more thoroughly").
> 
> https://lore.kernel.org/r/20190926124115.1.Ice34ad5970a375c3c03cb15c3859b3ee501561bf@changeid

Yes, I saw it and thanks for it =)

> > > > It should be possible to do a regulator_disable() though I'm not
> > > > sure anyone actually uses that.  The pattern for a regular
> > > > consumer should be the normal enable/disable pair to handle
> > > > shared usage, only an exclusive consumer should be able to use
> > > > just a straight disable.

In my case it is a regulator-fixed which uses the enable/disable pair.
But as my descriptions says this will not work currently because boot-on
marked regulators can't be disabled right now (using the same logic as
always-on regulators).

> > > Ah, I see, I wasn't aware of the "exclusive" special case!  Marco: is
> > > this working for you?  I wonder if we need to match
> > > "regulator->enable_count" to "rdev->use_count" at the end of
> > > _regulator_get() in the exclusive case...

So my fix isn't correct to fix this in general?

> > Yes, I think that case has been missed when adding the enable
> > counts - I've never actually had a system myself that made any
> > use of this stuff.  It probably needs an audit of the users to
> > make sure nobody's relying on the current behaviour though I
> > can't think how they would.
> 
> Marco: I'm going to assume you'll tackle this since I don't actually
> have any use cases that need this.

My use case is a simple regulator-fixed which is turned on by the
bootloader or to be more precise by the pmic-rom. To map that correctly
I marked this regulator as boot-on. Unfortunately as I pointed out above
this is handeld the same way as always-on.

Regards,
  Marco

> -Doug
> 

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