On Thu, 2021-07-01 at 10:25 -0500, Bjorn Helgaas wrote:
[...]
> After 27d868b5e6cfa, pci_configure_device() did actually call
> pcie_set_mps(), which updates the Device Control register (possibly
> restricted by dev->pcie_mpss, which is set by this quirk).
> 
> The fixup_mpss_256() quirk was added in 2011 by a94d072b2023 ("PCI:
> Add quirk for known incorrect MPSS").  Interesting that 27d868b5e6cfa
> was merged in 2015 but apparently nobody noticed until now.  I guess
> those Solarflare devices aren't widely used?
[...]

The key thing is that this quirk was working around an issue with
legacy interrupts, while the sfc and sfc-falcon drivers have always
preferred to use MSIs if available.  (But I also don't think many
SFC4000-based NICs were sold, and they were EOL'd about 10 years ago.)

Ben.
> 

-- 
Ben Hutchings
[W]e found...that it wasn't as easy to get programs right as we had
thought. I realized that a large part of my life from then on was going
to be spent in finding mistakes in my own programs.
                                                 - Maurice Wilkes, 1949