linux-kernel - Re: [PATCH] platform: set of_node in platform_device_register

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Message-ID: <CAJZ5v0gG5Rau71YrmUL8V7EpZjHQNOzLpEJHCJjXdgaDm4TrSw@mail.gmail.com>
Date:   Wed, 20 Feb 2019 10:50:43 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Måns Rullgård <mans@...sr.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform: set of_node in platform_device_register_full()

On Mon, Feb 18, 2019 at 12:10 PM Måns Rullgård <mans@...sr.com> wrote:
>
> "Rafael J. Wysocki" <rafael@...nel.org> writes:
>
> > On Sat, Feb 16, 2019 at 5:50 PM Mans Rullgard <mans@...sr.com> wrote:
> >>
> >> If the provided fwnode is an OF node, set dev.of_node as well.
> >>
> >> Signed-off-by: Mans Rullgard <mans@...sr.com>
> >> ---
> >>  drivers/base/platform.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> >> index dff82a3c2caa..853a1d0e5845 100644
> >> --- a/drivers/base/platform.c
> >> +++ b/drivers/base/platform.c
> >> @@ -512,6 +512,7 @@ struct platform_device *platform_device_register_full(
> >>
> >>         pdev->dev.parent = pdevinfo->parent;
> >>         pdev->dev.fwnode = pdevinfo->fwnode;
> >> +       pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode));
> >
> > of_node_get() generally does a kobject_get() on the node's kobject, so
> > when is that reference dropped?  Or if it doesn't need to be dropped
> > at all, why is this the case?
>
> platform_device_release() calls of_device_node_put().

Yes, it does, but this is the reference that's already acquired for
devices added while parsing DT, isn't it?

Your change adds an extra reference AFAICS.

Also, why is this patch needed?