Meh I screwed something up on 3.12.1 that would make cgminer just go idle eventually, so I've posted a hotfix 3.12.2 release.
Thanks! I still get an insanely long reset time though (minutes instead of seconds), while cgminer 3.12.2 is contemplating pages of these messages:
[2014-02-07 14:04:02] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
[2014-02-07 14:04:02] HFB 0 HFGetHeader usb read err:(-1) LIBUSB_ERROR_IO
[2014-02-07 14:04:03] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
[2014-02-07 14:04:03] HFB 0 HFGetHeader usb read err:(-1) LIBUSB_ERROR_IO
[2014-02-07 14:04:03] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
[2014-02-07 14:04:03] HFB 0 HFGetHeader usb read err:(-1) LIBUSB_ERROR_IO
[2014-02-07 14:04:03] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
[2014-02-07 14:04:03] HFB 0 HFGetHeader usb read err:(-1) LIBUSB_ERROR_IO
[2014-02-07 14:04:03] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
[2014-02-07 14:04:03] HFB 0 HFGetHeader usb read err:(-1) LIBUSB_ERROR_IO
[2014-02-07 14:04:03] HFB 0 attempted reset got err:(0) LIBUSB_SUCCESS
This is the usage difference over 7 hours:
