Re: [PATCH v4 01/29] Revert "treewide: Fix probing of devices in DT overlays"

Geert Uytterhoeven
2025-12-02T16:41:00Z

Hi Hervé,

On Tue, 2 Dec 2025 at 10:26, Herve Codina <herve.codina@bootlin.com> wrote:
> On Fri, 28 Nov 2025 10:34:57 +0200
> Kalle Niemi <kaleposti@gmail.com> wrote:
> > >>>>>> Test system testing drivers for ROHM ICs bisected this commit to cause
> > >>>>>> BD71847 drivers probe to not be called.
> > >>>>> This driver (and overlay support) is in linux-next or something out of
> > >>>>> tree on top of linux-next?
> > >>>>>
> > >>>>> Rob
> > >>>> Yes the driver is in mainline linux: /drivers/mfd/rohm-bd718x7.c
> > >>> I don't see any support to apply overlays in that driver.
> > >> Ah. Sorry for the confusion peeps. I asked Kalle to report this without
> > >> proper consideration. 100% my bad.
> > >>
> > >> While the bd718x7 drive indeed is mainline (and tested), the actual
> > >> 'glue-code' doing the overlay is part of the downstream test
> > >> infrastructure. So yes, this is not a bug in upstream kernel - this
> > >> falls in the category of an upstream change causing downstream things to
> > >> break. So, feel free to say: "Go fix your code" :)
> > >>
> > >> Now that this is sorted, if someone is still interested in helping us to
> > >> get our upstream drivers tested - the downstream piece is just taking
> > >> the compiled device-tree overlay at runtime (via bin-attribute file),
> > >> and applying it using the of_overlay_fdt_apply(). The approach is
> > >> working for our testing purposes when the device is added to I2C/SPI
> > >> node which is already enabled. However, in case where we have the I2C
> > >> disabled, and enable it in the same overlay where we add the new device
> > >> - then the new device does not get probed.
> > >>
> > >> I would be really grateful if someone had a pointer for us.
> > > Seems to be fw_devlink related. I suppose if you turn it off it works?
> > > There's info about the dependencies in sysfs or maybe debugfs. I don't
> > > remember the details, but that should help to tell you why things
> > > aren't probing.
>
> Rob reverted patches but I plan to continue my work on it.
> On my side, I need the reverted patches but I fully understand that, on
> your side, you need a working system.
>
> In order to move forward and find a solution for my next iteration, can you
> send your overlay (dtso) used in your working and non working cases?

Hmm, I must have missed when Rob applied (part of) this series, as I
do an overlay test (using the out-of-tree configfs) on top of every
(bi-weekly) renesas-drivers release, and saw no issues during the last
few months.

So I applied this series and tested loading my SPI EEPROM overlay.
And it indeed breaks, with the culprit being this particular patch.

Interestingly, quoting from this patch:

"While the commit fixed fw_devlink overlay handling for one case, it
broke it for another case. So revert it and redo the fix in a separate
patch."

Where is the separate patch that redid the fix? I assume it is "[PATCH
v4 03/29] of: dynamic: Fix overlayed devices not probing because
of fw_devlink"? Unfortunately that doesn't fix the issue for me.

Quoting more from this patch:

"Closes: https://lore.kernel.org/lkml/CAMuHMdXEnSD4rRJ-o90x4OprUacN_rJgyo8x6=9F9rZ+-KzjOg@mail.gmail.com/"

Strange that it claims to fix the issue reported there, as the failure
mode I am seeing is exactly the same as documented in that report?

Do you know what is wrong? The overlay I am using is referenced in
the bug report linked above.

Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds