Comment 12 for bug 1257591

I'm afraid I'm still stuck here:

# python tagtool.py -d nfc
[main] enable debug output for module 'nfc'
[nfc.clf] searching for reader with path 'usb'
[nfc.dev.transport] using pyusb version 0.x
[nfc.dev.transport] path matches '^(usb|)$'
[nfc.dev] trying usb:072f:2200
[nfc.dev] import nfc.dev.acr122
[nfc.dev.transport] >>> 6f050000000000000000ff00480000
[nfc.dev.transport] <<< 800a000000000002810041435231323255323133
Traceback (most recent call last):
  File "tagtool.py", line 479, in <module>
    TagTool().run()
  File "/home/joggler/nfc/nfcpy/examples/cli.py", line 283, in run
    while self.run_once() and self.options.loop:
  File "/home/joggler/nfc/nfcpy/examples/cli.py", line 230, in run_once
    try: clf = nfc.ContactlessFrontend(device)
  File "/home/joggler/nfc/nfcpy/nfc/clf.py", line 105, in __init__
    if path and not self.open(path):
  File "/home/joggler/nfc/nfcpy/nfc/clf.py", line 156, in open
    self.dev = nfc.dev.connect(path)
  File "/home/joggler/nfc/nfcpy/nfc/dev/__init__.py", line 64, in connect
    device = driver.init(usb)
  File "/home/joggler/nfc/nfcpy/nfc/dev/acr122.py", line 121, in init
    chipset = Chipset(transport)
  File "/home/joggler/nfc/nfcpy/nfc/dev/acr122.py", line 40, in __init__
    reader_version = self.ccid_xfr_block(bytearray.fromhex("FF00480000"))
  File "/home/joggler/nfc/nfcpy/nfc/dev/acr122.py", line 81, in ccid_xfr_block
    if len(frame) != 10 + struct.unpack("<I", frame[1:5])[0]:
struct.error: unpack requires a string argument of length 4

Running as root for time being to test, but always the same result.