I’m happy to report that this seems to have been a firmware issue: with a temporary install of MS Windows, which the card reader manufacturer’s firmware upgrading software required [1], I managed to upgrade the card reader’s bought-with firmware version 551 to manufacturer’s current latest version 563 (released just last month). After this there were no more ”disabled ep” messages in any boot, the reader works just fine and there have been no kernel panics of any kind.

This was with the mainline 3.8 kernel so I’m not marking this bug invalid just yet. I’ve now switched back to the Quantal kernel I initially reported this with and will report here next week on how it goes.

*[1] http://www.akasa.com.tw/update.php?tpl=product/cpu.product.tpl&no=181&type=Card%20Reader/Hub&type_sub=Card%20Reader&model=AK-ICR-17