Re: [PATCH v3] PCI: pciehp: Fix hotplug on Catlow Lake with unreliable PME status

Kuppuswamy Sathyanarayanan
2026-03-25T21:12:49Z

On 3/24/2026 11:11 PM, Mika Westerberg wrote:
> On Tue, Mar 24, 2026 at 02:45:25PM -0700, Kuppuswamy Sathyanarayanan wrote:
>>> eb34da60edee ("PCI: pciehp: Disable hotplug interrupt during suspend")
>>> cleared PCI_EXP_SLTCTL_HPIE so that when the link goes down, we
>>> wouldn't get a PCI_EXP_SLTSTA_DLLSC interrupt and wake the system.
>>>
>>> I don't know the details of why the PCI_EXP_SLTSTA_DLLSC would cause
>>> that wakeup. I would think pciehp should field that, and it should be
>>> able to figure out whether to bring the port out of D3hot.
>>>
>>> Anyway, with this patch it looks like we'll leave PCI_EXP_SLTCTL_HPIE
>>> set, and potentially get that PCI_EXP_SLTSTA_DLLSC interrupt again?
>>
>> I have tested this patch on Catlow Lake. Enabling HPIE does not result in
>> spurious wakeups as mentioned in Mika's patch.
>>
>> Mika, any comments?
>
> What do you have connected to the slot?

A network card.

>
> IIRC the interrupt triggers when presence change toggles (due to the link
> going down).
>

I have tested the s3 mode. I was able to see message related to system entering
suspend and then coming back again after (after user intervention). I also noted
pcie_disable_interrupt() called before suspend and pcie_enable_interrupt() called
after resume.

If required, I can repeat the test and collect logs.

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer