On Fri, Dec 01, 2017 at 11:08:46PM +0100, Christian Zigotzky wrote: > On 30.11.2017 23:42, Bjorn Helgaas wrote: > > > > 00:11.0 claims to be a PCIe Root Port leading to [bus 05-06]. That > > means there's a Link (presumably this A-Link II Express thing), and the > > downstream end of the Link *should* be a PCIe Upstream Port on bus 05, > > but no such device is visible. I suppose the SB600 does implement > > some sort of PCIe Port there, but keeps it invisible to software, and > > at the same time, contains an invisible bridge that connects the Link > > to all the conventional PCI devices on bus 05. > > > > When we scan bus 05, we do this: > > > > pci_scan_child_bus_extend(bus=05) > > for (devfn = 0; devfn < 0x100; devfn += 8) > > pci_scan_slot(05, 00.0) > > pci_scan_single_device > > pci_scan_device(05, 00.0) # fails; no 05:00.0 > > pci_scan_slot(05, 01.0) > > only_one_child(bus=05) > > parent = 00:11.0 > > pci_pcie_type(00:11.0) == ROOT_PORT # returns true > > > > Since only_one_child() sees that 00:11.0 is a Root Port, we give up > > before we even get to the PCI_SCAN_ALL_PCIE_DEVS test. > > > > I *think* something like the patch below should make this work if you > > use the "pci=pcie_scan_all" parameter. We have some x86 DMI quirks > > that set PCI_SCAN_ALL_PCIE_DEVS automatically. I don't know how to do > > something similar on powerpc, but maybe you do? > > > > Hi Bjorn, > > I tested your new patch today. It boots with the boot argument > "pci=pcie_scan_all". Well done! :-) > > It doesn't boot without the boot argument "pci=pcie_scan_all". Thanks for testing that. I'll merge a similar patch for v4.16. I don't think using "pci=pcie_scan_all" is really an acceptable long-term answer for you, though. Is there some way we can identify at run-time whether we're on a Nemo system? If so, we can make this happen automatically. Bjorn
