linux-kernel - Re: [PATCH 3/3] gpio: Add reference counting for non-exclusive GPIOs

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Message-ID: <20181127133033.GC3206@sirena.org.uk>
Date:   Tue, 27 Nov 2018 13:30:33 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        patches@...nsource.cirrus.com
Subject: Re: [PATCH 3/3] gpio: Add reference counting for non-exclusive GPIOs

On Mon, Nov 26, 2018 at 10:53:40PM +0100, Linus Walleij wrote:

> The managed resources pretty much assume
> that you tie resources to the device model and let kref inside the
> kobject in struct device do all refcounting and that essentially
> collides with the refcounting inside the regulator core, they both
> want to control this now.

If a driver is handing ownership of an object over to something else
then devm is always unsuitable.

> I suspect maybe the lesser evil is to bite the bullet, invent
> gpiod_get_from_of_node() which is the missing API (we currently
> only have devm_gpiod_get_from_of_node()) and simply
> fix up the converted regulator drivers to avoid devm_*
> retrieveal in the same manner as wm8994 (the already
> queued patch). This will make the regulator core own the
> refcounting as it does today.

You're always going to need unmanaged versions of functions for use with
things like this I think.

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