> A web search shows some similar reports (e.g.
> <https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1329566>,
>
<http://askubuntu.com/questions/473848/ubuntu-14-04-realtek-semiconductor-co-ltd-rts5227-pci-express-card-reader-isn>).
> But in that last one, it turns out that the out-of-tree driver does
> work.

Indeed, that is a workaround - download from
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=15&PFid=25&Level=4&Conn=3&DownTypeID=3&GetDown=false
, apply the attached patch, remove all rtsx_* modules, and insert the
new rts2557 module into the kernel.