Re: [PATCH] PCI/DPC: Extend DPC recovery timeout

[Ethan Zhao <etzhao1900@gmail.com>]

On 8/7/2025 5:52 AM, Keith Busch wrote:
> On Wed, Aug 06, 2025 at 04:34:09PM -0500, Bjorn Helgaas wrote:
>>>> However, the current 4 seconds timeout in pci_dpc_recovered() is indeed
>>>> an empirical value rather than a hard requirement from the PCIe
>>>> specification. In real-world scenarios, like with Mellanox ConnectX-5/7
>>>> adapters, we've observed that full DPC recovery can take more than 5-6
>>>> seconds, which leads to premature hotplug processing and device removal.
>>>
>>> I think Sathya's point was:  Have you made an effort to talk to the
>>> vendor and ask them to root-cause and fix the issue e.g. with a firmware
>>> update.
>>
>> Would definitely be great, but unless we have a number in the spec to
>> point to, they might just shrug and ask what the requirement is.
> 
> I agree, and I have similar problems with other arbitrary kernel timing
> decicsions. Specifically RRL where there's no spec defined number yet my
> patch to modify it has not received much consideration.
> 
>    https://lore.kernel.org/linux-pci/20250218165444.2406119-1-kbusch@meta.com/
> 
At least, with this patch, have a workaround in hand to make some device 
work.

Thanks,
Ethan