[PATCH v3 3/9] PCI: of_property: Restore the arguments of the next level parent

Claudiu
2025-07-04T16:36:34Z

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

of_pci_make_dev_node() creates a device tree node for the PCIe bridge it
detects. The node name follows the format: pci_type@pci_slot,pci_func. If
such a node already exists in the current device tree, a new one is not
created.

When the node is created, its contents are populated with information from
the parent node. In the case of root complex nodes described in the device
tree, the created node duplicates the interrupt-map property. However, the
duplicated interrupt-map property does not correctly point to the next
interrupt controller.

For example, in the case of the Renesas RZ/G3S SoC, the resulting device
tree node is as follows (only relevant DT properties are shown):

pcie@11e40000 {

// ...

interrupt-map = <0x00 0x00 0x00 0x01 0x1f 0x00 0x00 0x00 0x00
0x00 0x00 0x00 0x02 0x1f 0x00 0x00 0x00 0x01
0x00 0x00 0x00 0x03 0x1f 0x00 0x00 0x00 0x02
0x00 0x00 0x00 0x04 0x1f 0x00 0x00 0x00 0x03>;
interrupt-map-mask = <0x00 0x00 0x00 0x07>;
interrupt-controller;
#interrupt-cells = <0x01>;

#address-cells = <0x03>;
#size-cells = <0x02>;

phandle = <0x1f>;

// ...

pci@0,0 {
reg = <0x00 0x00 0x00 0x00 0x00>;
interrupt-map = <0x10000 0x00 0x00 0x01 0x1f 0x00 0x11e40000 0x00 0x00
0x10000 0x00 0x00 0x02 0x1f 0x00 0x11e40000 0x00 0x01
0x10000 0x00 0x00 0x03 0x1f 0x00 0x11e40000 0x00 0x02
0x10000 0x00 0x00 0x04 0x1f 0x00 0x11e40000 0x00 0x03>;
interrupt-map-mask = <0xffff00 0x00 0x00 0x07>;
#interrupt-cells = <0x01>;

#address-cells = <0x03>;
#size-cells = <0x02>;

// ...
};
};

With this pci@0,0 node, the interrupt-map parsing code behaves as follows:

When a PCIe endpoint is enumerated and it requests to map a legacy
interrupt, of_irq_parse_raw() is called requesting the interrupt from
pci@0,0. If INTA is requested, of_irq_parse_raw() first matches:

interrupt-map = <0x10000 0x00 0x00 0x01 0x1f 0x00 0x11e40000 0x00 0x00>

from the pci@0,0 node. It then follows the phandle 0x1f to the interrupt
parent, looking for a mapping for interrupt ID 0x00
(0x00 0x11e40000 0x00 0x00). However, the root complex node does not
provide this mapping in its interrupt-map property, causing the interrupt
request to fail.

To avoid this, in the interrupt-map property of the nodes generated by
of_pci_make_dev_node() map legacy interrupts to entries that are valid in
the next level interrupt controller in the interrupt mapping tree.

With this, the generated pci@0,0 node and its parent look as follows:

pcie@11e40000 {
// ...

interrupt-map = <0x00 0x00 0x00 0x01 0x1f 0x00 0x00 0x00 0x00
0x00 0x00 0x00 0x02 0x1f 0x00 0x00 0x00 0x01
0x00 0x00 0x00 0x03 0x1f 0x00 0x00 0x00 0x02
0x00 0x00 0x00 0x04 0x1f 0x00 0x00 0x00 0x03>;
interrupt-map-mask = <0x00 0x00 0x00 0x07>;
interrupt-controller;
#interrupt-cells = <0x01>;

#address-cells = <0x03>;
#size-cells = <0x02>;

phandle = <0x1f>;

// ...

pci@0,0 {
reg = <0x00 0x00 0x00 0x00 0x00>;
interrupt-map = <0x10000 0x00 0x00 0x01 0x1f 0x00 0x11e40000 0x00 0x01
0x10000 0x00 0x00 0x02 0x1f 0x00 0x11e40000 0x00 0x02
0x10000 0x00 0x00 0x03 0x1f 0x00 0x11e40000 0x00 0x03
0x10000 0x00 0x00 0x04 0x1f 0x00 0x11e40000 0x00 0x04>;
interrupt-map-mask = <0xffff00 0x00 0x00 0x07>;
#interrupt-cells = <0x01>;

#address-cells = <0x03>;
#size-cells = <0x02>;
};
};

Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none; this patch is new

drivers/pci/of_property.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 506fcd507113..8dfed096326f 100644
--- a/drivers/pci/of_property.c
+++ b/drivers/pci/of_property.c
@@ -243,6 +243,14 @@ static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
}
of_property_read_u32(out_irq[i].np, "#address-cells",
&addr_sz[i]);
+
+ /*
+ * Restore the arguments of the next level parent if a map
+ * was found.
+ */
+ out_irq[i].np = pnode;
+ out_irq[i].args_count = 1;
+ out_irq[i].args[0] = pin;
}

list_for_each_entry(child, &pdev->subordinate->devices, bus_list) {
--
2.43.0