[PPC] Boot problems after the pci-v6.18-changes

[Bjorn Helgaas]

On Wed, Nov 12, 2025 at 04:40:18AM +0100, Christian Zigotzky wrote:
> On 11/11/2025 01:20 PM, Bjorn Helgaas wrote:
> > On Tue, Nov 11, 2025 at 06:15:20AM +0100, Christian Zigotzky wrote:
> >> On 11/07/2025 06:06 AM, Christian Zigotzky wrote:
> >>> On 11/05/2025 11:09 PM, Bjorn Helgaas wrote:
> >>>>> I tested your patch with the RC4 of kernel 6.18 today. Unfortunately
> >>> it
> >>>>> doesn't solve the boot issue.
> >>>>
> >>>> Thanks for testing that.  I see now why that approach doesn't work:
> >>>> quirk_disable_aspm_l0s_l1() calls pci_disable_link_state(), which
> >>>> updates the permissible ASPM link states, but pci_disable_link_state()
> >>>> only works for devices at the downstream end of a link.  It doesn't
> >>>> work at all for Root Ports, which are at the upstream end of a link.
> >>>>
> >>>> Christian, you originally reported that both X5000 and X1000 were
> >>>> broken.  I suspect X1000 may have been fixed in v6.18-rc3 by
> >>>> df5192d9bb0e ("PCI/ASPM: Enable only L0s and L1 for devicetree
> >>>> platforms"), but I would love to have confirmation of that.
> >>>
> >>> Hello Bjorn,
> >>>
> >>> I will enable CONFIG_PCIEASPM and CONFIG_PCIEASPM_DEFAULT for the RC5 of
> >>> kernel 6.18 and test it with the X1000.
> >>
> >> I tested the RC5 of kernel 6.18 with CONFIG_PCIEASPM and
> >> CONFIG_PCIEASPM_DEFAULT enabled on my X1000 today. Unfortunately the boot
> >> problems are still present.
> >
> > Thanks.  Can you post a dmesg somewhere so I can see what the relevant
> > device IDs are?  Can be with any kernel, doesn't have to be v6.18.  We
> > need the Vendor and Device IDs to add a quirk.
> 
> X1000 kernel 6.18.0-rc5 dmesg:
> https://github.com/user-attachments/files/23491291/dmesg_x1000.txt

Thanks!  This shows all the Root Ports are [1959:a002]:

  pci 0000:00:10.0: [1959:a002] type 01 class 0x060400 PCIe Root Port
  pci 0000:00:10.0: PCI bridge to [bus 01]
  pci 0000:01:00.0: [1002:6898] type 00 class 0x030000 PCIe Legacy Endpoint

I'm confused because Hypexed's 6.18.0-a7-dmesg.log from
https://github.com/chzigotzky/kernels/issues/17#issuecomment-3400419966
shows the same Root Ports, and apparently it booted fine even though
we enabled *everything*: 

  pci 0000:00:10.0: [1959:a002] type 01 class 0x060400 PCIe Root Port
  pci 0000:00:10.0: PCI bridge to [bus 01]
  pci 0000:01:00.0: [1002:6610] type 00 class 0x030000 PCIe Legacy Endpoint
  pci 0000:01:00.0: ASPM: DT platform, enabling L0s-up L0s-dw L1 ASPM-L1.1 ASPM-L1.2 PCI-PM-L1.1 PCI-PM-L1.2

It's *possible* that ASPM doesn't work on your endpoint (AMD Cypress
XT [Radeon HD 5870]) but does work on Hypexed's endpoint (AMD Oland XT
[Radeon HD 8670 / R5 340X OEM / R7 250/350/350X OEM]), but that seems
unlikely to me.

Maybe we just give up on ASPM on the [1959:a002] device.  A web search
doesn't show many users of it, so I don't know how many people would
care.

Bjorn