linux-kernel - Re: [PATCH RFT/RFC] mfd: cs42l43: setup true links with software nodes

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Message-ID: <CAMRc=Mck8MiAm_nxY_L6Zw4cH-vYf24zSkPp=bhnUw68Q6FV=g@mail.gmail.com>
Date: Wed, 19 Nov 2025 11:50:09 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc: David Rhodes <david.rhodes@...rus.com>, Richard Fitzgerald <rf@...nsource.cirrus.com>, 
	Lee Jones <lee@...nel.org>, Mark Brown <broonie@...nel.org>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Linus Walleij <linus.walleij@...aro.org>, Maciej Strozek <mstrozek@...nsource.cirrus.com>, 
	Andy Shevchenko <andy@...nel.org>, linux-sound@...r.kernel.org, 
	patches@...nsource.cirrus.com, linux-kernel@...r.kernel.org, 
	linux-spi@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH RFT/RFC] mfd: cs42l43: setup true links with software nodes

On Wed, Nov 19, 2025 at 11:47 AM Charles Keepax
<ckeepax@...nsource.cirrus.com> wrote:
>
> On Wed, Nov 19, 2025 at 11:38:35AM +0100, Bartosz Golaszewski wrote:
> > On Wed, Nov 19, 2025 at 10:58 AM Charles Keepax
> > <ckeepax@...nsource.cirrus.com> wrote:
> > >
> > > > > > Hi Charles!
> > > > > >
> > > > > > Please give this a try. It's only build-tested so far. I hope I
> > > > > > understood correctly that it's the SPI driver that needs the "cs" GPIO
> > > > > > from the pinctrl.
> > > > >
> > > > > Unfortunately it fails with an -EBUSY on adding the MFD children.
> > > > > I will investigate a little more and report back.
> > > >
> > > > Does it fail in device_add_software_node() in MFD core? Is it possible
> > > > that the device already has a software node for some reason?
> > >
> > > Yeah it seems there is already a software node, although somewhat
> > > at a loss as to why, the only ones we add are inside the SPI
> > > driver. I will poke further and see if I can find out how it
> > > acquires that node.
> > >
> >
> > Let me know if you figure it out, I'll submit a v2 that doesn't drop
> > the undefined swnode.
>
> Cool, thanks for all your help here. Might take me a couple hours
> but I will get to the bottom of the EBUSY thing, and report back.
>

Sure. Could you just post the stack trace down to where the EBUSY is
returned in drivers/base/swnode.c? I'd like to analyze the logic
myself too if that's not too much work for you.

Bart