linux-kernel - Re: [PATCH v3 02/10] software node: increase the reference of the swnode by its fwnode

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Message-ID: <aQSsPIJ26Sx2WqhE@smile.fi.intel.com>
Date: Fri, 31 Oct 2025 14:31:56 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Krzysztof Kozlowski <krzk@...nel.org>, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 02/10] software node: increase the reference of the
 swnode by its fwnode

On Fri, Oct 31, 2025 at 05:27:10AM -0500, Bartosz Golaszewski wrote:
> On Fri, 31 Oct 2025 10:44:46 +0100, Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> said:
> > On Fri, Oct 31, 2025 at 10:03:47AM +0100, Bartosz Golaszewski wrote:
> >> On Fri, Oct 31, 2025 at 9:30 AM Andy Shevchenko
> >> <andriy.shevchenko@...ux.intel.com> wrote:
> >> > On Thu, Oct 30, 2025 at 03:33:02AM -0700, Bartosz Golaszewski wrote:
> >> > > On Thu, 30 Oct 2025 10:34:46 +0100, Andy Shevchenko
> >> > > <andriy.shevchenko@...ux.intel.com> said:

...

> >> > > Andy: the resulting code after patch 3/10 looks like this:
> >> > >
> >> > > struct fwnode_handle *refnode;
> >> > >
> >> > > (...)
> >> >
> >> > Let's say something like below to be put here
> >> >
> >> > /*
> >> >  * The reference in software node may refer to a node of a different type.
> >> >  * Depending on the type we choose either to use software node directly, or
> >> >  * delegate that to fwnode API.
> >> >  */
> >>
> >> But this is incorrect: we're not really doing that. We either use the
> >> firmware node reference directly OR cast the software node to its
> >> firmware node representation. We ALWAYS use the firmware node API
> >> below.
> >>
> >> This really *is* evident from the code but if it'll make you happy and
> >> make you sign off on this, I'll add a corrected version.
> >
> > The comment should answer to the Q: "Why the heck are we calling fwnode APIs here?"
> >
> >> IMO It's completely redundant.
> >
> > This is unusual case for swnode API (see other functions, they call directly
> > the low-level implementation instead of going to a round via fwnode). That's
> > why I insist on a comment of this piece. It may be obvious for you, but the
> > unprepared read would be surprised by this inconsistency.
> >
> 
> I propose to have the following:
> 
> +       /*
> +        * A software node can reference other software nodes or firmware
> +        * nodes (which are the abstraction layer sitting on top of them).
> +        * This is done to ensure we can create references to static software
> +        * nodes before they're registered with the firmware node framework.
> +        * At the time the reference is being resolved, we expect the swnodes
> +        * in question to already have been registered and to be backed by
> +        * a firmware node. This is why we use the fwnode API below to read the
> +        * relevant properties and bump the reference count.
> +        */
> 
> This at least adds relevant information on *why* we're using the fwnode API.

Yes, works for me, thanks!

-- 
With Best Regards,
Andy Shevchenko