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

[Herve Codina]

Hi Kalle,

On Fri, 28 Nov 2025 10:34:57 +0200
Kalle Niemi <kaleposti@xxxxxxxxx> wrote:

...
> >>>>>>
> >>>>>> Hello,
> >>>>>>
> >>>>>> 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?

Best regards,
Hervé