On 8/14/2025 5:39 PM, Rui He wrote:
For preconfigured PCI bridge, child bus created on the first scan.
While for some reasons(e.g register mutation), the secondary, and subordiante
register reset to 0 on the second scan, which caused to create
PCI bus twice for the same PCI device.
Following is the related log:
[Wed May 28 20:38:36 CST 2025] pci 0000:0b:01.0: PCI bridge to [bus 0d]
[Wed May 28 20:38:36 CST 2025] pci 0000:0b:05.0: bridge configuration invalid ([bus 00-00]), reconfiguring
[Wed May 28 20:38:36 CST 2025] pci 0000:0b:01.0: PCI bridge to [bus 0e-10]
[Wed May 28 20:38:36 CST 2025] pci 0000:0b:05.0: PCI bridge to [bus 0f-10]
Could you help to attach a 'lspci -t' about the topology ?
bridge 0000:0b:01.0 and 0000:0b:05.0 have the same subordinate
bus number, that is weird seems they aren't connected as upstream
and downstream, but siblings.
Does the device behind the bridge 0000:0b:05.0 work after the
second scan (TLP are forwarded) ?>
Here PCI device 000:0b:01.0 assigend to bus 0d and 0e.
This patch checks if child PCI bus has been created on the second scan
of bridge. If yes, return directly instead of create a new one.
Signed-off-by: Rui He <rui.he@xxxxxxxxxxxxx>
---
drivers/pci/probe.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index f41128f91ca76..ec67adbf31738 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1444,6 +1444,9 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
goto out;
}
The bridge should was marked as broken=1 already, bailed out earlier,
wouldn't get here with bridge forwarding was disabled. no further
configuration anymore. what is your kernel number ?
Thanks,
Ethan> + if(pci_has_subordinate(dev))
+ goto out;
+
/* Clear errors */
pci_write_config_word(dev, PCI_STATUS, 0xffff);
