umass: differences between RELENG_5 and -current?

I've got the following device which basically works under -current:

umass0: SigmaTel, Inc. USBMSC Audio Player, rev 1.10/0.01, addr 2
umass0: SCSI over Bulk-Only; quirks = 0x0000
umass0: Get Max Lun not supported (STALLED)
umass0:2:0:-1: Attached to scbus2
da1 at umass-sim0 bus 0 target 0 lun 0
da1: <SigmaTel MSCN 0001> Removable Direct Access SCSI-4 device 
da1: 1.000MB/s transfers
da1: 123MB (251904 512 byte sectors: 64H 32S/T 123C)

(It panics the system when I unmount a msdosfs on it, but accessing it
through mtools works well.)

Under RELENG_5, all I get is:

umass0: SigmaTel, Inc. USBMSC Audio Player, rev 1.10/0.01, addr 5
usbd_setup_pipe: failed to start endpoint, IOERROR
device_attach: umass0 attach returned 6

The differences between the umass.c files between both systems aren't
exciting, so I guess it's something else.  Does anyone have a hint for
me where to look?  I'd like to get it supported under -stable as well
if possible.

If anyone is interested in seeing the msdosfs unmount panic, I can
send a trace as well (but I'd rather update to a recent -current
before then to make sure the problem still persists).

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)