Subject: Re: [PATCH v3 3/3] ARM: at91: remove unnecessary of_platform_default_populate calls

From: Miquel Raynal <[email-masked]>
Date: Mon, 27 Apr 2026 17:07:01 +0200

Hi Alexander,

On 24/04/2026 at 12:56:27 +02, Alexander Dahl <[email-masked]> wrote:

> Hei hei,
>
> after few hints in IRC yesterday, I tried to understand why neither
> the ebi driver nor the nand driver are probed, but I failed.  See
> below.

Just to be clear, I would not expect the NAND driver to probe "alone",
it is described as a child node of the EBI controller which has its own
compatible. As a result, only the of_platform_populate() at the end of
the probe of the EBI can lead to the NAND controller to probe. The EBI
node being a child node of a "simple-bus", this is the one we should
focus on, because it should be probed.

One reason (trying to be creative) could the that Rob's patch is
dropping an explicit populate that maybe kind of bypasses checks that
the "official" populate does. So maybe there is one resource that is
missing and which is not ignored as it used to be by the core device
driver (likely, dd.c).

Can you enable CONFIG_DEBUG_DRIVER and see in the logs if anything pops
up? Maybe trying to trace (manually) in the core why we do not attempt
to probe the EBI controller by looking for possible conditions to bail
out early. Pinctrl is one of them, so maybe just removing all pinctrl
references in the DT may help troubleshooting this (obviously probe will
fail if pinctrl is incorrect, but if it is attempted we will have a
culprit).

Good luck,
Miquèl