[openfabrics-ewg] Drop in performance on Mellanox MT25204 single port DDR HCA

[Roland Dreier]

Does using the "tune_pci=1" module option for ib_mthca bring the
performance back up?

The reason the driver was changed to work this way is that presumably
the BIOS is setting the PCI configuration as it does for a reason.  So
you might want investigate why the BIOS sets MaxReadReq down to 128 in
the first place.  (removing the save/restore across reset lets the HCA
pick a new default for all the settings, but may cause problems by
getting rid of BIOS settings, which we assume were done for a reason).

However tune_pci=1 will make the driver override this setting if you
really know what you're doing.

 - R.