Re: [PATCH v2 3/7] irqdomain: Add parent field to struct irqchip_fwid

Lorenzo Pieralisi
2026-01-07T17:32:01Z

On Wed, Jan 07, 2026 at 10:04:52AM +0000, Jonathan Cameron wrote:
> On Wed, 7 Jan 2026 09:58:07 +0100
> Lorenzo Pieralisi <lpieralisi@kernel.org> wrote:
>
> > On Mon, Jan 05, 2026 at 12:01:08PM +0000, Jonathan Cameron wrote:
> > > On Thu, 18 Dec 2025 11:14:29 +0100
> > > Lorenzo Pieralisi <lpieralisi@kernel.org> wrote:
> > >
> > > > The GICv5 driver IRQ domain hierarchy requires adding a parent field to
> > > > struct irqchip_fwid so that core code can reference a fwnode_handle parent
> > > > for a given fwnode.
> > > >
> > > > Add a parent field to struct irqchip_fwid and update the related kernel API
> > > > functions to initialize and handle it.
> > > >
> > > > Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
> > > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > > Cc: Marc Zyngier <maz@kernel.org>
> > > Hi Lorenzo,
> > >
> > > Happy new year.
> >
> > Happy New Year !
> >
> > > > ---
> > > > include/linux/irqdomain.h | 30 ++++++++++++++++++++++++++----
> > > > kernel/irq/irqdomain.c | 14 +++++++++++++-
> > > > 2 files changed, 39 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
> > > > index 62f81bbeb490..b9df84b447a1 100644
> > > > --- a/include/linux/irqdomain.h
> > > > +++ b/include/linux/irqdomain.h
> > > > @@ -257,7 +257,8 @@ static inline void irq_domain_set_pm_device(struct irq_domain *d, struct device
> > > >
> > > > #ifdef CONFIG_IRQ_DOMAIN
> > > > struct fwnode_handle *__irq_domain_alloc_fwnode(unsigned int type, int id,
> > > > - const char *name, phys_addr_t *pa);
> > > > + const char *name, phys_addr_t *pa,
> > > > + struct fwnode_handle *parent);
> > > >
> > > > enum {
> > > > IRQCHIP_FWNODE_REAL,
> > > > @@ -267,18 +268,39 @@ enum {
> > > >
> > > > static inline struct fwnode_handle *irq_domain_alloc_named_fwnode(const char *name)
> > > > {
> > > > - return __irq_domain_alloc_fwnode(IRQCHIP_FWNODE_NAMED, 0, name, NULL);
> > > > + return __irq_domain_alloc_fwnode(IRQCHIP_FWNODE_NAMED, 0, name, NULL, NULL);
> > > > +}
> > > > +
> > > > +static inline
> > > > +struct fwnode_handle *irq_domain_alloc_named_fwnode_parent(const char *name,
> > > > + struct fwnode_handle *parent)
> > >
> > > The name of this makes me think it's allocating the named fwnode parent, rather that
> > > the named fwnode + setting it's parent.
> > >
> > > There aren't all that many calls to irq_domain_named_fwnode(), maybe to avoid challenge
> > > of a new name, just add the parameter to all of them? (25ish) Mind you the current
> > > pattern for similar cases is a helper, so maybe not.
> >
> > Similar cases ? Have you got anything specific I can look into ?
>
> I meant all the different irq_domain_alloc_xxxxx variants that call
> __irq_domain_alloc_fwnode() with a subset of parameters set to NULL.
>
> That seems to say there is a precedence for making the presence of the parameter
> part of the name rather than requiring callers to set the ones they don't want to
> NULL. So it argues for a helper like this one just for consistency.

Yep that's why I wrote it this way but that does not mean it can't be
changed.

> >
> > > Or go with something similar to named and have
> > >
> > > irq_domain_alloc_named_parented_fwnode()?
> >
> > Or I can add a set_parent() helper (though that's a bit of churn IMO) ?
> >
> > If Thomas has a preference I will follow that, all of the above is doable
> > for me.
>
> Agreed. Let's see what Thomas prefers (i.e. make the decision his problem ;)

Thomas do you have any preference on the matter please ? It is not a big deal
either way I'd just like to respin promptly (provided the rest of the series
does not require further changes other than the ones Jon suggested and I
addressed) if possible please.

Thanks,
Lorenzo

> Jonathan
>
> >
> > > I'm not that bothered though if you think the current naming is the best we can do.
> >
> > I think you have a point - as per my comment above.
> >
> > Thanks,
> > Lorenzo
> >
> > > Jonathan
> > >
> > > > +{
> > > > + return __irq_domain_alloc_fwnode(IRQCHIP_FWNODE_NAMED, 0, name, NULL, parent);
> > > > }
> > >
> > >
> >
>