So the TP-Link GPL tarball has, in a Linux 3.14 tree, what looks like something of a hybrid between a backported mmc driver and their own development. It's newer than the one in Linux 3.14 actual, but it contains strings and code I cannot find in any subsequent Linux driver either.
Or I'm just completely missing something here that should be obvious. Why would they run a completely parallel development track - they're not exactly making their own silicon.