On Thu, Jan 27, 2022 at 03:46:15PM +0100, Mariusz Tkaczyk wrote: > ... > Thanks for your suggestions. Blazej did some tests and results were > inconclusive. He tested it on two same platforms. On the first one it > didn't work, even if he reverted all suggested patches. On the second > one hotplugs always worked. > > He noticed that on first platform where issue has been found initally, > there was boot parameter "pci=nommconf". After adding this parameter > on the second platform, hotplugs stopped working too. > > Tested on tag pci-v5.17-changes. He have CONFIG_HOTPLUG_PCI_PCIE > and CONFIG_DYNAMIC_DEBUG enabled in config. He also attached two dmesg > logs to bugzilla with boot parameter 'dyndbg="file pciehp* +p" as > requested. One with "pci=nommconf" and one without. > > Issue seems to related to "pci=nommconf" and it is probably caused > by change outside pciehp. Maybe I'm missing something. If I understand correctly, the problem has nothing to do with the kernel version (correct me if I'm wrong!) PCIe native hotplug doesn't work when booted with "pci=nommconf". When using "pci=nommconf", obviously we can't access the extended PCI config space (offset 0x100-0xfff), so none of the extended capabilities are available. In that case, we don't even ask the platform for control of PCIe hotplug via _OSC. From the dmesg diff from normal (working) to "pci=nommconf" (not working): -Command line: BOOT_IMAGE=/boot/vmlinuz-smp ... +Command line: BOOT_IMAGE=/boot/vmlinuz-smp pci=nommconf ... ... -acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM ClockPM Segments MSI HPX-Type3] -acpi PNP0A08:00: _OSC: platform does not support [AER LTR] -acpi PNP0A08:00: _OSC: OS now controls [PCIeHotplug PME PCIeCapability] +acpi PNP0A08:00: _OSC: OS supports [ASPM ClockPM Segments MSI HPX-Type3] +acpi PNP0A08:00: _OSC: not requesting OS control; OS requires [ExtendedConfig ASPM ClockPM MSI] +acpi PNP0A08:00: MMCONFIG is disabled, can't access extended PCI configuration space under this bridge. Why are you using "pci=nommconf"? As far as I know, there's no reason to use that except to work around some kind of defect. Bjorn
