PCI: of: Update parent unit address generation in of_pci_prop_intr_map()

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 hardware 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 (i.e., 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 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@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/lkml/aJms+YT8TnpzpCY8@lpieralisi/
Link: https://patch.msgid.link/20250818093504.80651-1-lpieralisi@kernel.org

0 files changed, 0 insertions, 0 deletions