linux-kernel - Re: [PATCH 3/9] software node: allow referencing firmware nodes

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Message-ID: <aPcuHpYCM22NZ7S_@kekkonen.localdomain>
Date: Tue, 21 Oct 2025 09:54:22 +0300
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...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 3/9] software node: allow referencing firmware nodes

Hi Bartosz, Andy,

On Mon, Oct 20, 2025 at 01:26:59PM +0200, Bartosz Golaszewski wrote:
> On Mon, Oct 20, 2025 at 12:05 PM Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com> wrote:
> >
> > > >
> > > > Can't we always have an fwnode reference?
> > >
> > > Unfortunately no. A const struct software_node is not yet a full
> > > fwnode, it's just a template that becomes an actual firmware node when
> > > it's registered with the swnode framework. However in order to allow
> > > creating a graph of software nodes before we register them, we need a
> > > way to reference those templates and then look them up internally in
> > > swnode code.
> >
> > Strange that you need this way. The IPU3 bridge driver (that creates a graph of
> > fwnodes at run-time for being consumed by the respective parts of v4l2
> > framework) IIRC has no such issue. Why your case is different?
> >
> 
> From what I can tell the ipu-bridge driver only references software
> nodes (as struct software_node) from other software nodes. I need to
> reference ANY implementation of firmware node from a software node.

Yes, the IPU bridge only references software nodes.

I might use two distinct pointers instead of an union and an integer field
that tells which type is the right one. I don't expect more such cases
here; it's either a software node or an fwnode handle (ACPI or OF node).

-- 
Regards,

Sakari Ailus