On 02 December 2017 at 00:27PM, Bjorn Helgaas wrote:
> 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
>
Hi Bjorn,
Hi All,
Olof Johansson has created a patch for us. With this patch,
"pci=pcie_scan_all" executes automatically on P.A. Semi boards. We don't
need to add 'pci=pcie_scan_all' to the
kernel boot arguments anymore. Could you please add Olof's patch to the
official kernel source code?
arch/powerpc/platforms/pasemi/pci.c | 2 ++
1 file changed, 2 insertions(+)
Thanks,
Christian
