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

[Christian Zigotzky]

> On 15 October 2025 at 03:51 pm, Herve Codina <herve.codina at bootlin.com> wrote:
> 
> Hi Christian,
> 
> On Wed, 15 Oct 2025 15:14:28 +0200
> Christian Zigotzky <chzigotzky at xenosoft.de> wrote:
> 
>>> Am 15 October 2025 at 02:59 pm, Herve Codina <herve.codina at bootlin.com> wrote:
>>> 
>>> Also when it boots, it is not easy to know about the problem root cause.
>>> 
>>> In my case, it was not obvious to make the relationship on my side between
>>> my ping timings behavior and ASPM.
>>> 
>>> Of course 'git bisect' helped a lot but can we rely on that for the average
>>> user?
>>> 
>>> Best regards,
>>> Hervé  
>> 
>> I think I will revert these modifications for the RC2.
> 
> I don't know what is the future of those modifications but maybe instead
> of fully reverting them, maybe you could perform calls to
> - pcie_clkpm_override_default_link_state() and
> - pcie_aspm_override_default_link_state()
> only if a new Kconfig symbol is enabled.
> 
> Of course this symbols will be disabled by default but if you want some
> people to test behavior, it could be interesting to have the code
> available in the kernel.
> 
> I don't know, this was just an idea.
> 
> Of course, reverting the patch is simpler than adding this new Kconfig
> symbol.
> 
> Best regards,
> Hervé

Hi Hervé,

Do you mean an option in the kernel config? If yes, then it is a great idea.

@Mani
Could you please create an option in the kernel config that enable or disable the power management for PCI and PCI Express?
If yes, then I don’t need to revert the changes due to boot issues and less performance.

Just for info: Simon Richter wrote:

Intel B580 on TalosII has trouble growing the BAR with 6.18.

Power management changes should not affect PPC because it is broken anyway — PCIe bridges are assumed to be managed by OpenFirmware, so the "pcieport" driver is not registered, so bridges have no power management, so downstream devices cannot enable it either.

- - -

Thanks,
Christian