I also have two of those devices. I am even more unlucky
as I have yet to see the RESET message. The devices tend to
work more reliable on USB 1.1.

My failure pattern is:
  Install device in ehci port
  Read succeed at reasonable speed (~6Mbyte/sec)
  newfs -2 /dev/sd0a show the CSW error messages
  USB to that device stalls
  unplugging doesn't clear up the situation
  -> reboot

Another thing that has cropped up lately is the
umass: no memory
error. This does not happen right after boot, it is very likely after X
has been started. So currently plugging in a USB memory device is
coupled with a re-boot 8-(. This happens with 2.99.9 and 2.99.10
(last check a week ago).

Regards,
  Frank

> Some devices are just plain buggy when it comes to the CSW handling.
> You could try disabling that check in umass by setting the appropriate
> quirk for the device.
>
> 	-- Lennart
>
> Vincent wrote:
>> Hi there,
>> I've tried a couple of USB 2.0 DoC (memory sticks) today. While they
>> work fine when one reads data, they fail on write.
>>
>> Here is what I get:
>>
>> umass0 at uhub2 port 1 configuration 1 interface 0
>> umass0: Pen Drive USB DISK 2.0, rev 2.00/1.00, addr 2
>> umass0: using SCSI over Bulk-Only
>> scsibus0 at umass0: 2 targets, 1 lun per target
>> sd0 at scsibus0 target 0 lun 0: <, USB DISK 2.0, PMAP> disk removable
>> sd0: 246 MB, 984 cyl, 32 head, 16 sec, 512 bytes/sect x 503808 sectors
>> [...]
>> umass0: Invalid CSW: tag 55518 should be 55519
...
>> umass0: Invalid CSW: tag 55542 should be 55543
>> umass0: BBB reset failed, TIMEOUT
>> umass0: BBB bulk-in clear stall failed, TIMEOUT
>> umass0: at uhub2 port 1 (addr 2) disconnected
>> sd0(umass0:0:0:0): generic HBA error
>>
...