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

[Maciej W. Rozycki]

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