Re: [PATCH] soc: fsl: qe: properly scan GPIO nodes at startup

[Christophe Leroy (CS GROUP)]

Hi Hervé,

Le 29/07/2026 à 17:21, Herve Codina a écrit :
> Hi Christophe,
>
> On Wed, 29 Jul 2026 16:10:36 +0200
> "Christophe Leroy (CS GROUP)" <chleroy@xxxxxxxxxx> wrote:
>
> > Before commit 156460811def ("soc: fsl: qe: Change GPIO driver to a
> > proper platform driver") qe_add_gpiochips() was walking the device
> > tree to find all nodes with compatible "fsl,mpc8323-qe-pario-bank".
> >
> > After that commit the discovery is handled by the platform core,
> > therefore it is necessary to call of_platform_default_populate() on
> > the par_io node.
> >
> > Fixes: 156460811def ("soc: fsl: qe: Change GPIO driver to a proper platform driver")
> > Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@xxxxxxxxxx>
> > ---
> >   drivers/soc/fsl/qe/qe_io.c | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> >
> > diff --git a/drivers/soc/fsl/qe/qe_io.c b/drivers/soc/fsl/qe/qe_io.c
> > index a5e2d0e5ab51..02ca556c8db0 100644
> > --- a/drivers/soc/fsl/qe/qe_io.c
> > +++ b/drivers/soc/fsl/qe/qe_io.c
> > @@ -15,6 +15,7 @@
> >   #include <linux/errno.h>
> >   #include <linux/module.h>
> >   #include <linux/ioport.h>
> > +#include <linux/of_platform.h>
> >   
> >   #include <asm/io.h>
> >   #include <soc/fsl/qe/qe.h>
> > @@ -184,3 +185,17 @@ int par_io_of_config(struct device_node *np)
> >   	return 0;
> >   }
> >   EXPORT_SYMBOL(par_io_of_config);
> > +
> > +static int __init par_io_populate(void)
> > +{
> > +	struct device_node *np = of_find_node_by_name(NULL, "par_io");
> > +
> > +	if (!np)
> > +		return 0;
> > +
> > +	of_platform_default_populate(np, NULL, NULL);
> > +	of_node_put(np);
> > +
> > +	return 0;
> > +}
> > +arch_initcall(par_io_populate);
>
>
> The par_io node is a sub-node of the soc@xxx node.
> The soc@xxx node is simple-bus compatible. This child node should be
> populated.
>
> Why do we need this additional of_platform_default_populate?
>
> Also par_io node has a compatible. Maybe the related driver should call
> of_platform_populate() to populate children of par_io if needed. If this
> driver is missing, maybe it should be created.
>
> Do I miss something?

As discussed together off-line, at the time being the par_io driver is 
not a platform driver. par_io_init() is called from setup_arch() by some 
board setups.

In order to fix the regression, I keep it minimal with an 
arch_initcall() function which is equivalent to what we had before 
changing this driver to a platform driver. It will also ease applying 
the fix to stable without too much churn.

It will still be possible to rework par_io driver in a follow-up patch 
and change it to a propoer platform driver.

Christophe