[PATCH 0/1] PCI set flag PCI_SCAN_ALL_PCIE_DEVS for P.A. Semi boards

[Christian Zigotzky <chzigotzky@xenosoft.de>]

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