Comment 0 for bug 1991366

[SRU Justification]

[Impact]
Some Dell laptops where booting with Thunderbolt/USB4 devices connected the BIOS leaves some of
the PCIe devices unconfigured. The kernel message shows "No bus number available for hot-added bridge". The connected devices can't be found.

[Fix]
Current linux PCI distribute the "spare" resources between hotplug ports on hot-add but have not done that upon the initial scan. The patches make the initial root bus scan path to do the same.

[Test]
1. Power on the machine with Thunderbolt/USB4 devices connected.
2. Check the kernel message to see if "No bus number available for hot-added bridge" shows up or not.
3. Check if the Thunderbolt/USB4 devices works or not.

[Where problems could occur]
The patches only apply the same procedures on initial root bus scan which was not done. If the BIOS configures the PCI correctly, everything is OK. It only takes effect for the BIOS w/ unconfigured PCIe devices.