On Mon, Aug 18, 2025 at 11:35:04AM +0200, Lorenzo Pieralisi wrote: > Some interrupt controllers require an #address-cells property in their > bindings without requiring a "reg" property to be present. > > The current logic used to craft an interrupt-map property in > of_pci_prop_intr_map() is based on reading the #address-cells > property in the interrupt-parent and, if != 0, read the interrupt > parent "reg" property to determine the parent unit address to be > used to create the parent unit interrupt specifier. > > First of all, it is not correct to read the "reg" property of > the interrupt-parent with an #address-cells value taken from the > interrupt-parent node, because the #address-cells value define the > number of address cells required by child nodes. > > More importantly, for all modern interrupt controllers, the parent > unit address is irrelevant in HW in relation to the > device<->interrupt-controller connection and the kernel actually > ignores the parent unit address value when hierarchically parsing > the interrupt-map property (ie of_irq_parse_raw()). > > For the reasons above, remove the code parsing the interrupt > parent "reg" property in of_pci_prop_intr_map() - it is not > needed and as it is it is detrimental in that it prevents > interrupt-map property generation on systems with an > interrupt-controller that has no "reg" property in its > interrupt-controller node - and leave the parent unit address > always initialized to 0 since it is simply ignored by the kernel. > > Signed-off-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: Rob Herring <robh@xxxxxxxxxx> > Cc: Lizhi Hou <lizhi.hou@xxxxxxx> > Link: https://lore.kernel.org/lkml/aJms+YT8TnpzpCY8@lpieralisi/ Applied to pci/of for v6.18, thanks, Lorenzo! > --- > drivers/pci/of_property.c | 21 ++++++++++++++------- > 1 file changed, 14 insertions(+), 7 deletions(-) > > diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c > index 506fcd507113..09b7bc335ec5 100644 > --- a/drivers/pci/of_property.c > +++ b/drivers/pci/of_property.c > @@ -279,13 +279,20 @@ static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs, > mapp++; > *mapp = out_irq[i].np->phandle; > mapp++; > - if (addr_sz[i]) { > - ret = of_property_read_u32_array(out_irq[i].np, > - "reg", mapp, > - addr_sz[i]); > - if (ret) > - goto failed; > - } > + > + /* > + * A device address does not affect the > + * device<->interrupt-controller HW connection for all > + * modern interrupt controllers; moreover, the kernel > + * (ie of_irq_parse_raw()) ignores the values in the > + * parent unit address cells while parsing the interrupt-map > + * property because they are irrelevant for interrupts mapping > + * in modern system. > + * > + * Leave the parent unit address initialized to 0 - just > + * take into account the #address-cells size to build > + * the property properly. > + */ > mapp += addr_sz[i]; > memcpy(mapp, out_irq[i].args, > out_irq[i].args_count * sizeof(u32)); > -- > 2.48.0 >
