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

[Herve Codina <herve.codina@bootlin.com>]

Hi Christophe,

On Thu, 30 Jul 2026 10:11:29 +0200
"Christophe Leroy (CS GROUP)" <chleroy@kernel.org> wrote:

> 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@kernel.org> 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@kernel.org>
> >> ---
> >>   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.
> 

Yes, indeed, this makes sense.

Thanks for the clarification.

Best regards,
Hervé