I have a Kingston KNE40BT ethernet card which has a "tulip" digital 21041-PB
chip in it. I get loads of "receive ring overrun"s. I have NMBCLUSTER=4096,
and it seems that there is an initial period after reboot during which the
card seems work OK, and then the overruns commence, which gives the
impression that "something" is getting full.

const struct tlp_pci_quirks tlp_pci_21041_quirks[] = {
    { tlp_pci_dec_quirks,       { 0x08, 0x00, 0x2b } },
    { tlp_pci_dec_quirks,       { 0x00, 0x00, 0xf8 } },
    { NULL,             { 0, 0, 0 } }
};

are mentioned, but this thing has a 00-C0-F0 address. Any thoughts on where
to start? (There is no phy involved)

Cheers,

Patrick