[Libusb-devel] Nomad Jukebox software using libusb is not getting highspeed transfers

[Artur B. <ar...@dz...>]

Hi everybody,

I've got curious problem using libnjb software to communicate with my
Nomad Jukebox Zen USB 2.0 device under Linux (several versions tried,
currently using 2.4.22-pre7) over PCI USB 2.0 interface (two different
ones, actually, based on VIA and ALi chips). libnjb uses libusb
(0.1.7) to communicate with the device.

The device itself is detected by Linux just fine as USB 2.0 highspeed
device:

T:  Bus=01 Lev=01 Prnt=01 Port=04 Cnt=01 Dev#=  6 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=ff(vend.) Sub=ff Prot=ff MxPS=64 #Cfgs=  2
P:  Vendor=041e ProdID=410b Rev= 0.01
S:  Manufacturer=Creative Technology
S:  Product=NOMAD Jukebox Zen (USB 2.0)
S:  SerialNumber=15FF0A8323491017
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=440mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
C:  #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=440mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms

All transfers, however, are limited to USB 1.1 fullspeed (ie. not
exceeding 10-12 Mbps range). The problem is not tied to the jukebox
itself (under Windows it easily achieves 40-60 Mbps and more over USB
2.0 interface) nor the USB 2.0 card/Linux driver (I tested the
interface by hooking up external USB 2.0 hard disk and the performance
is quite satisfactory, with transfers in 60-80 Mbps range).

A quick review of libnjb software shows that it uses pretty
straightforward libusb interface (mostly usb_control_msg and
usb_bulk_read/write). Do you have any suggestions regarding what might
be the reason for such problem? If there is any libusb tweak I could
use to get more information/force highspeed transfer, please let me
know.

Thanks in advance for any help/suggestions.

-- 
   ___ ___   -------------------------------------------------------
  / _ | _ )   Artur "Archie" Bartnicki
 / __ | _ \   mailto:ar...@dz...
/_/ |_|___/  -------------------------------------------------------

In a cat's eye, all things belong to cats.