Hello Folks,

At least one intel chipset will occasionally negotiate a 4x link for an 8x 
device in an 8x port.  It is a known errata in the 5400 mch.  Simply 
disabling and re-enabling the link is all that is required to restore full 
throughput.  Toggling the retrain bit in the pci-e link control register 
alone is insufficient.

I have added a small bit of code to the pcie port device which checks for 
this condition and attempts to retrain the link.  It is possible that it 
will give a false positive if the port is capable of accepting lesser 
width devices.  This should be harmless although I would not rule out poor 
implementations having issues with gratuitous retraining.

Thanks,
Jeff