linux-kernel - Re: [PATCH 06/15 v3] regulator: max8973: Let core handle GPIO descriptor

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Date:   Thu, 6 Dec 2018 12:47:46 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 06/15 v3] regulator: max8973: Let core handle GPIO descriptor

On Thu, Dec 6, 2018 at 11:34 AM Charles Keepax
<ckeepax@...nsource.cirrus.com> wrote:
> On Thu, Dec 06, 2018 at 09:58:30AM +0100, Linus Walleij wrote:
> > On Wed, Dec 5, 2018 at 4:33 PM Charles Keepax
> > <ckeepax@...nsource.cirrus.com> wrote:
> > > On Wed, Dec 05, 2018 at 03:42:06PM +0100, Linus Walleij wrote:
> > > > On Wed, Dec 5, 2018 at 2:43 PM Charles Keepax
> > > > <ckeepax@...nsource.cirrus.com> wrote:
> > > > > On Wed, Dec 05, 2018 at 01:47:12PM +0100, Linus Walleij wrote:
> > > > > > @@ -775,10 +779,13 @@ static int max8973_probe(struct i2c_client *client,
> > > > > >               /*
> > > > > >                * We do not let the core switch this regulator on/off,
> > > > > >                * we just leave it on.
> > > > > > +              *
> > > > > > +              * Do not use devm* here: the regulator core takes over the
> > > > > > +              * lifecycle management of the GPIO descriptor.
> > > > > >                */
> > > > > > -             gpiod = devm_gpiod_get_optional(&client->dev,
> > > > > > -                                             "maxim,enable",
> > > > > > -                                             GPIOD_OUT_HIGH);
> > > > > > +             gpiod = gpiod_get_optional(&client->dev,
> > > > > > +                                        "maxim,enable",
> > > > > > +                                        GPIOD_OUT_HIGH);
> > > > >
> > > > > My comment on v2 still stands here, the GPIO is not passed to
> > > > > the regulator core on this path.
> > > >
> > > > Patch 01 should take care of that, did you check it?
> > >
> > > Yeah, patch 1 makes the regulator core consistently handle GPIOs
> > > that are passed into it.
> >
> > Sorry. I confused this patch for the max77686 patch. That
> > one was fixed with patch 01...
> >
> > > However, on the MAX77621 path in this
> > > switch statement the GPIO is never passed into the regulator
> > > core, so the core never takes ownership of it, so the driver still
> > > needs to manage the lifetime.
> > >
> > > It should be a pretty easy fix though as commented on v2, again
> > > apologies for the slow review.
> >
> > OK I switch it to devm_ as you suggested, as we implemented
> > gpiod_unhinge it's a piece of cake nowadays.
> >
>
> You shouldn't really need to use unhinge, you can just use devm
> on the path that doesn't pass it to the core and not on the
> one that does. You just need to update the error case below it to
> use config->ena_gpiod rather than gpiod.

Indeed I just think it will be confusing when people read the code.

It's better consistency if its just devm_* and the  we unhinge the
one we pass to the regulator core IMO.

Yours,
Linus Walleij