linux-kernel - Re: [PATCH v3 18/28] of: property: Allow fw_devlink device-tree on x86 when PCI device-tree node creation is enabled

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Message-ID: <CAL_JsqJCuevzu69bx3yWm3ZR9wZ+UsWuNXscig5KMm2WH4WxOw@mail.gmail.com>
Date: Fri, 27 Jun 2025 12:49:36 -0500
From: Rob Herring <robh@...nel.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Herve Codina <herve.codina@...tlin.com>, Andrew Lunn <andrew@...n.ch>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Danilo Krummrich <dakr@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Andi Shyti <andi.shyti@...nel.org>, 
	Wolfram Sang <wsa+renesas@...g-engineering.com>, Peter Rosin <peda@...ntia.se>, 
	Derek Kiernan <derek.kiernan@....com>, Dragan Cvetic <dragan.cvetic@....com>, 
	Arnd Bergmann <arnd@...db.de>, Saravana Kannan <saravanak@...gle.com>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Mark Brown <broonie@...nel.org>, Len Brown <lenb@...nel.org>, 
	Daniel Scally <djrscally@...il.com>, Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Wolfram Sang <wsa@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Davidlohr Bueso <dave@...olabs.net>, 
	Dave Jiang <dave.jiang@...el.com>, Alison Schofield <alison.schofield@...el.com>, 
	Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, 
	Dan Williams <dan.j.williams@...el.com>, linux-kernel@...r.kernel.org, 
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-clk@...r.kernel.org, linux-i2c@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-pci@...r.kernel.org, 
	linux-spi@...r.kernel.org, linux-acpi@...r.kernel.org, 
	linux-cxl@...r.kernel.org, Allan Nielsen <allan.nielsen@...rochip.com>, 
	Horatiu Vultur <horatiu.vultur@...rochip.com>, 
	Steen Hegelund <steen.hegelund@...rochip.com>, Luca Ceresoli <luca.ceresoli@...tlin.com>, 
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v3 18/28] of: property: Allow fw_devlink device-tree on
 x86 when PCI device-tree node creation is enabled

On Fri, Jun 27, 2025 at 11:33 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Fri, Jun 27, 2025 at 11:22:45AM -0500, Rob Herring wrote:
> > On Fri, Jun 13, 2025 at 03:47:58PM +0200, Herve Codina wrote:
>
> ...
>
> > > -   if (IS_ENABLED(CONFIG_X86))
> > > +   if (IS_ENABLED(CONFIG_X86) && !IS_ENABLED(CONFIG_PCI_DYNAMIC_OF_NODES))
> >
> > I really want CONFIG_PCI_DYNAMIC_OF_NODES to go away at some point, not
> > add more users.
> >
> > I think this should instead check for specific platforms not with
> > kconfig symbols but DT properties. For ce4100, you can just check the
> > root compatible string. For OLPC, there isn't a root compatible (in the
> > DT I have). You could check for /architecture == OLPC instead. There's
> > some virtualization guests using DT now too. I would think their DT's
> > are simple enough to avoid any fw_devlink issues.
>
> I don't think this is good approach. The above check is more reliable in my
> opinion.

I'm fine with any solution that doesn't add a
CONFIG_PCI_DYNAMIC_OF_NODES which we can't remove. Adding it was a
kick the can down the road to merge the support worry the mixed
usecase (on ACPI systems) later. It's now later.

> > Alternatively, we could perhaps make x86 fw_devlink default off
>
> For my (little) knowledge I believe this is not feasible anymore.
> Some x86 code (drivers) relies on fw_devlink nowadays. But take
> this with grain of salt, I may be way mistaken.

Doesn't the CONFIG_X86 check disable it?

Rob