Hi,

During a process of testing Aviage MMS applications for iPods through USB on the target hardware, a very interesting 
behavior of the io-usb is observed. The 3rd Gen Nano iPod can only work through a usb hub. If without the hub, io-usb 
will fail to get the device descriptor hence fail to recognize the iPod. From sloginof, the following error messages are
 prompted out.

Time             Sev Major Minor Args
Jan 01 00:28:35    2    12     0 CLASS_ExtractDevice:  no parent
Jan 01 00:28:36    2    12     0 CLASS_EnumerateDevice: bus 0, parent 0, port 0, speed 2
Jan 01 00:28:36    2    12     0 CLASS_EnumerateDevice:  Get device descriptor
Jan 01 00:28:36    2    12     0 EHCI - Error on Control Transfer ( 0x88248, 0x30086000 0x154120 ) - Retrying 
transfer(count 1)
Jan 01 00:28:36    2    12     0 EHCI - Error on Control Transfer ( 0x88248, 0x30086000 0x154120 ) - Retrying 
transfer(count 2)
...
J0x30086000 0x154120 ) - Retrying transfer(count 32)
Jan 01 00:28:36    2    12     0 EHCI - Error on Control Transfer ( 0x88248, 0x30086000 0x154120 )
Jan 01 00:28:36    2    12     0 CLASS_EnumerateDevice:  Get device descriptor failed 5


Here are the details of the hub.
USB 0 (EHCI) v1.10, v1.01 DDK, v1.01 HCD
    Control, Interrupt, Bulk(SG), Isoch(Stream), Low speed, High speed

Device Address             : 1
Upstream Host Controller   : 0
Upstream Device Address    : 0
Upstream Port              : 0
Upstream Port Speed        : High
Vendor                     : 0x0409 (NEC)
Product                    : 0x005a
Device Release             : r1.00
USB Spec Release           : v2.00
Serial Number              : N/A
Class                      : 0x09 (Hub)
Subclass                   : 0x00
Protocol                   : 0x01
Max PacketSize0            : 64
Languages                  : No string descriptors
Current Frame              : 11207 (1024 bytes)
Hub Number Ports           : 4
Hub Characteristics        : 0x00a9 (Individual power, Individual over-current)
Hub Power On->Good         : 100 ms
Hub Power Requirements     : 100 mA
Configurations             : 1
  Configuration            : 1
    Attributes             : 0xe0 (Self-powered, Remote-wakeup)
    Max Power              : 100 mA
    Interfaces             : 1
      Interface            : 0 / 0
        Class              : 0x09 (Hub)
        Subclass           : 0x00
        Protocol           : 0x00
        Endpoints          : Control + 1
          Endpoint         : 0
            Attributes     : Control
            Max Packet Size: 64

Then I tried another hub for the 3G Nano iPod, the issue becomes more interesting. In this time io-usb can only get the 
device descriptor through the hub but fail in set configuration state. 
The followings are the sloginfo and the detail of the hub.
Time             Sev Major Minor Args
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDevice: bus 0, parent 1, port 1, speed 2
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDevice:  Get device descriptor
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDevice:  Set address 3
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDevice:  Get full device descriptor
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDeviceConfiguration:  Get config descriptor
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDeviceConfiguration:  Get full config descriptor
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDeviceConfiguration:  Get config descriptor
Jan 01 00:53:36    2    12     0 CLASS_EnumerateDeviceConfiguration:  Get full config descriptor
Jan 01 00:53:36    2    12     0 EHCI - Error on Control Transfer ( 0x558148, 0x30406003 0x154520 ) - Retrying 
transfer(count 1)
Jan 01 00:53:36    2    12     0 USB_SelectConfiguration:  Set config devno 3, cfg 1
Jan 01 00:53:36    2    12     0 EHCI - Error on Control Transfer ( 0x80008148, 0x30406003 0x154520 ) - Retrying 
transfer(count 1)
Jan 01 00:53:36    2    12     0 EHCI - Error on Control...