Re: [RFC] PCI: Fix the issue of link speed downgrade after link retraining

From: Maciej W. Rozycki
Date: Mon Nov 11 2024 - 07:50:45 EST


On Fri, 8 Nov 2024, Lukas Wunner wrote:

> > > Some printing information can be obtained when the issue emerges.
> > > "Card present" is reported twice via external interrupts due to
> > > a slight tremor when the Samsung NVMe device is plugged in.

What do you mean by "a slight tremor"? Do the devices involved fail to
negotiate link in the time prescribed by the PCIe specification? Why is
the interrupt sent twice?

> > > To avoid wrongly setting the link speed to 2.5GT/s, only allow
> > > specific pcie devices to perform link retrain.
>
> With which kernel version are you seeing this?
>
> A set of fixes for the 2.5GT/s retraining feature appeared in v6.12-rc1,
> specifically f68dea13405c ("PCI: Revert to the original speed after PCIe
> failed link retraining").
>
> Have you tested whether the latest v6.12 rc is still affected?

Thanks for chiming in. I do hope the fixes will have addressed issues
like one concerned here.

NB I have been fully booked recently due to an upcoming patch submission
deadline and will continue to be throughout this week, so I may be slow to
response.

Maciej