[PATCH 2/4] pci: fix DT node matching when reg encodes a non-zero bus number

[Sascha Hauer <s.hauer@pengutronix.de>]

pci_of_match_device() compared (reg[0] >> 8) & 0xffff against devfn, but
devfn is only 8 bits. The standard PCI DT binding encodes the bus number
in bits [23:16] of reg[0], so any child node with a non-zero bus byte -
which is the common upstream convention - yielded (bus << 8) | devfn and
never matched a plain devfn. For a typical host -> root port -> endpoint
DT nesting (e.g. pci@0,0 { reg = <0x300000 ...>; ethernet@0,0 { reg =
<0x310000 ...>; }; }), the root port match failed and scanning never
reached the endpoint, so endpoint properties like local-mac-address were
never picked up.

Mask with 0xff to match only the devfn byte, like Linux's
of_pci_get_devfn().

Assisted-by: Claude Opus 4.7
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/pci/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 32624fe05b..8d18889109 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -558,7 +558,7 @@ pci_of_match_device(struct device *parent, unsigned int devfn)
 			 * address, other properties are defined by the
 			 * PCI/OF node topology.
 			 */
-			reg = (reg >> 8) & 0xffff;
+			reg = (reg >> 8) & 0xff;
 			if (reg == devfn)
 				return np;
 		}

-- 
2.47.3