...
I made several tests concerning the topic and incidentally found one bug. :)
Here they go ...
$ cat /sys/module/usbcore/parameters/old_scheme_first
N
...
[ 0.000000] Kernel command line: ... usbcore.old_scheme_first=0 ...
<TEST-1>
...
[ 1.023403] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.406396] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 1.583398] usb 2-3: device descriptor read/64, error -71
[ 1.882430] usb 2-3: device descriptor read/64, error -71
[ 2.086434] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.284465] usb 2-3: device descriptor read/64, error -71
[ 2.583467] usb 2-3: device descriptor read/64, error -71
[ 2.788455] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.252449] usb 2-3: device not accepting address 5, error -71
[ 3.356458] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.821385] usb 2-3: device not accepting address 6, error -71
[ 4.143409] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 9.322407] usb 4-3: not running at top speed; connect to a high speed hub
[ 9.338413] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 9.338414] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 9.338415] usb 4-3: Product: Flash Disk
[ 9.338416] usb 4-3: Manufacturer: USB
[ 10.147223] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 10.147741] scsi8 : usb-storage 4-3:1.0
[ 10.147815] usbcore: registered new interface driver usb-storage
<TEST-2>
...
[ 1.033385] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.234421] usb 2-3: device descriptor read/64, error -71
[ 1.723407] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 1.926388] usb 2-3: device descriptor read/64, error -71
[ 2.225435] usb 2-3: device descriptor read/64, error -71
[ 2.430495] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.629410] usb 2-3: device descriptor read/64, error -71
[ 3.116409] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.315406] usb 2-3: device descriptor read/64, error -71
[ 3.614406] usb 2-3: device descriptor read/64, error -71
[ 3.819415] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 4.017405] usb 2-3: device descriptor read/64, error -71
[ 4.315405] usb 2-3: device descriptor read/64, error -71
[ 4.519406] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 4.984468] usb 2-3: device not accepting address 7, error -71
[ 5.087468] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 5.551463] usb 2-3: device not accepting address 8, error -71
[ 5.876416] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 11.058447] usb 4-3: not running at top speed; connect to a high speed hub
[ 11.074418] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 11.076701] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 11.078985] usb 4-3: Product: Flash Disk
[ 11.081261] usb 4-3: Manufacturer: USB
[ 11.578024] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 11.578275] scsi8 : usb-storage 4-3:1.0
[ 11.578783] usbcore: registered new interface driver usb-storage
<TEST-3>
...
[ 1.027406] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.229405] usb 2-3: device descriptor read/64, error -71
[ 1.716435] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 1.915403] usb 2-3: device descriptor read/64, error -71
[ 2.214431] usb 2-3: device descriptor read/64, error -71
[ 2.419422] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.617398] usb 2-3: device descriptor read/64, error -71
[ 2.916407] usb 2-3: device descriptor read/64, error -71
[ 3.120398] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.585454] usb 2-3: device not accepting address 5, error -71
[ 3.689457] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 4.153394] usb 2-3: device not accepting address 6, error -71
[ 4.475391] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 4.655438] usb 4-3: not running at top speed; connect to a high speed hub
[ 4.671402] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 4.673556] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 4.675696] usb 4-3: Product: Flash Disk
[ 4.677858] usb 4-3: Manufacturer: USB
[ 10.828081] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 10.829432] scsi8 : usb-storage 4-3:1.0
[ 10.829503] usbcore: registered new interface driver usb-storage
<TEST-4>
...
[ 1.022389] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.413397] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 1.612415] usb 2-3: device descriptor read/64, error -71
[ 1.913368] usb 2-3: device descriptor read/64, error -71
[ 2.118406] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.317478] usb 2-3: device descriptor read/64, error -71
[ 2.617394] usb 2-3: device descriptor read/64, error -71
[ 2.822461] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.288438] usb 2-3: device not accepting address 5, error -71
[ 3.392445] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.858434] usb 2-3: device not accepting address 6, error -71
[ 4.184387] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 4.364424] usb 4-3: not running at top speed; connect to a high speed hub
[ 4.380425] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 4.382573] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 4.384752] usb 4-3: Product: Flash Disk
[ 4.386883] usb 4-3: Manufacturer: USB
[ 10.082785] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 10.085269] scsi8 : usb-storage 4-3:1.0
[ 10.087663] usbcore: registered new interface driver usb-storage
~~~~~~~~~~~~~~
$ cat /sys/module/usbcore/parameters/old_scheme_first
N
$ cat /sys/module/usbcore/parameters/initial_descriptor_timeout
0
...
[ 0.000000] Kernel command line: ... usbcore.old_scheme_first=0
usbcore.initial_descriptor_timeout=0 ...
<TEST-5>
...
[ 1.023371] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.219390] usb 2-3: device descriptor read/64, error -71
[ 1.743371] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 1.929426] usb 4-3: not running at top speed; connect to a high speed hub
[ 1.944420] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 1.946270] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1.948130] usb 4-3: Product: Flash Disk
[ 1.949938] usb 4-3: Manufacturer: USB
[ 1.956081] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 1.958080] scsi8 : usb-storage 4-3:1.0
[ 1.960050] usbcore: registered new interface driver usb-storage
<TEST-6>
...
[ 1.023409] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.221415] usb 2-3: device descriptor read/64, error -71
[ 1.520411] usb 2-3: device descriptor read/64, error -71
[ 1.722748] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 1.921446] usb 2-3: device descriptor read/64, error -71
[ 2.220451] usb 2-3: device descriptor read/64, error -71
[ 2.425437] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.890399] usb 2-3: device not accepting address 4, error -71
[ 2.994405] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.459393] usb 2-3: device not accepting address 5, error -71
[ 3.738420] usb 4-3: new full-speed USB device number 2 using ohci-pci
~~~~~~~~~~~~~~
~~~~~~~~~~~~~~
$ cat /sys/module/usbcore/parameters/old_scheme_first
Y
...
[ 0.000000] Kernel command line: ... usbcore.old_scheme_first=1 ...
<TEST-1>
...
[ 1.029405] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.493373] usb 2-3: device not accepting address 2, error -71
[ 1.595426] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 2.062379] usb 2-3: device not accepting address 3, error -71
[ 2.166416] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.551476] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.015462] usb 2-3: device not accepting address 5, error -71
[ 3.119466] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.583401] usb 2-3: device not accepting address 6, error -71
[ 3.686401] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 3.884401] usb 2-3: device descriptor read/64, error -71
[ 4.182403] usb 2-3: device descriptor read/64, error -71
[ 4.386401] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 4.584403] usb 2-3: device descriptor read/64, error -71
[ 4.882391] usb 2-3: device descriptor read/64, error -71
[ 5.304396] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 5.328412] usb 4-3: not running at top speed; connect to a high speed hub
[ 5.344414] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 5.346480] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 5.348504] usb 4-3: Product: Flash Disk
[ 5.350441] usb 4-3: Manufacturer: USB
[ 5.357103] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 5.359106] scsi8 : usb-storage 4-3:1.0
[ 5.361119] usbcore: registered new interface driver usb-storage
<TEST-2>
...
[ 1.023779] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.511660] usb 2-3: device not accepting address 2, error -71
[ 1.615216] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 2.080187] usb 2-3: device not accepting address 3, error -71
[ 2.184218] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.569262] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.033202] usb 2-3: device not accepting address 5, error -71
[ 3.137255] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.601184] usb 2-3: device not accepting address 6, error -71
[ 3.705192] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 3.903206] usb 2-3: device descriptor read/64, error -71
[ 4.201191] usb 2-3: device descriptor read/64, error -71
[ 4.405190] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 4.603189] usb 2-3: device descriptor read/64, error -71
[ 4.901211] usb 2-3: device descriptor read/64, error -71
[ 5.216253] usb 2-3: new high-speed USB device number 9 using ehci-pci
[ 5.680248] usb 2-3: device not accepting address 9, error -71
[ 5.784250] usb 2-3: new high-speed USB device number 10 using ehci-pci
[ 6.248247] usb 2-3: device not accepting address 10, error -71
[ 6.352249] usb 2-3: new high-speed USB device number 11 using ehci-pci
[ 6.550249] usb 2-3: device descriptor read/64, error -71
[ 6.849279] usb 2-3: device descriptor read/64, error -71
[ 7.054252] usb 2-3: new high-speed USB device number 12 using ehci-pci
[ 7.252250] usb 2-3: device descriptor read/64, error -71
[ 7.551248] usb 2-3: device descriptor read/64, error -71
[ 7.974182] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 7.997197] usb 4-3: not running at top speed; connect to a high speed hub
[ 8.012200] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 8.014106] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 8.016052] usb 4-3: Product: Flash Disk
[ 8.017963] usb 4-3: Manufacturer: USB
[ 8.023856] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 8.025932] scsi8 : usb-storage 4-3:1.0
[ 8.027931] usbcore: registered new interface driver usb-storage
<TEST-3>
...
[ 1.024433] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.487397] usb 2-3: device not accepting address 2, error -71
[ 1.591455] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 2.058425] usb 2-3: device not accepting address 3, error -71
[ 2.162461] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.547502] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.011483] usb 2-3: device not accepting address 5, error -71
[ 3.115489] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.579487] usb 2-3: device not accepting address 6, error -71
[ 3.683490] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 4.068494] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 4.532430] usb 2-3: device not accepting address 8, error -71
[ 4.635433] usb 2-3: new high-speed USB device number 9 using ehci-pci
[ 5.099425] usb 2-3: device not accepting address 9, error -71
[ 5.202490] usb 2-3: new high-speed USB device number 10 using ehci-pci
[ 5.400489] usb 2-3: device descriptor read/64, error -71
[ 5.885494] usb 2-3: new high-speed USB device number 11 using ehci-pci
[ 6.349427] usb 2-3: device not accepting address 11, error -71
[ 6.453430] usb 2-3: new high-speed USB device number 12 using ehci-pci
[ 6.917491] usb 2-3: device not accepting address 12, error -71
[ 7.021492] usb 2-3: new high-speed USB device number 13 using ehci-pci
[ 7.220490] usb 2-3: device descriptor read/64, error -71
[ 7.519489] usb 2-3: device descriptor read/64, error -71
[ 7.724490] usb 2-3: new high-speed USB device number 14 using ehci-pci
[ 8.110490] usb 2-3: new high-speed USB device number 15 using ehci-pci
[ 8.574487] usb 2-3: device not accepting address 15, error -71
[ 8.678490] usb 2-3: new high-speed USB device number 16 using ehci-pci
[ 9.142484] usb 2-3: device not accepting address 16, error -71
[ 9.246433] usb 2-3: new high-speed USB device number 17 using ehci-pci
[ 9.444430] usb 2-3: device descriptor read/64, error -71
[ 9.743489] usb 2-3: device descriptor read/64, error -71
[ 9.948405] usb 2-3: new high-speed USB device number 18 using ehci-pci
[ 10.146490] usb 2-3: device descriptor read/64, error -71
[ 10.445429] usb 2-3: device descriptor read/64, error -71
[ 10.760430] usb 2-3: new high-speed USB device number 19 using ehci-pci
[ 11.224486] usb 2-3: device not accepting address 19, error -71
[ 11.327489] usb 2-3: new high-speed USB device number 20 using ehci-pci
[ 11.791486] usb 2-3: device not accepting address 20, error -71
[ 11.894494] usb 2-3: new high-speed USB device number 21 using ehci-pci
[ 12.092490] usb 2-3: device descriptor read/64, error -71
[ 12.390489] usb 2-3: device descriptor read/64, error -71
[ 12.594428] usb 2-3: new high-speed USB device number 22 using ehci-pci
[ 12.792489] usb 2-3: device descriptor read/64, error -71
[ 13.090489] usb 2-3: device descriptor read/64, error -71
[ 13.405490] usb 2-3: new high-speed USB device number 23 using ehci-pci
[ 13.869431] usb 2-3: device not accepting address 23, error -71
[ 13.972432] usb 2-3: new high-speed USB device number 24 using ehci-pci
[ 14.436487] usb 2-3: device not accepting address 24, error -71
[ 14.539489] usb 2-3: new high-speed USB device number 25 using ehci-pci
[ 14.737490] usb 2-3: device descriptor read/64, error -71
[ 15.035428] usb 2-3: device descriptor read/64, error -71
[ 15.239489] usb 2-3: new high-speed USB device number 26 using ehci-pci
[ 15.437489] usb 2-3: device descriptor read/64, error -71
[ 15.735489] usb 2-3: device descriptor read/64, error -71
[ 16.050434] usb 2-3: new high-speed USB device number 27 using ehci-pci
[ 16.514487] usb 2-3: device not accepting address 27, error -71
[ 16.617489] usb 2-3: new high-speed USB device number 28 using ehci-pci
[ 17.081424] usb 2-3: device not accepting address 28, error -71
[ 17.184430] usb 2-3: new high-speed USB device number 29 using ehci-pci
[ 17.382430] usb 2-3: device descriptor read/64, error -71
[ 17.680429] usb 2-3: device descriptor read/64, error -71
[ 17.884434] usb 2-3: new high-speed USB device number 30 using ehci-pci
[ 18.082430] usb 2-3: device descriptor read/64, error -71
[ 18.380429] usb 2-3: device descriptor read/64, error -71
[ 18.695490] usb 2-3: new high-speed USB device number 31 using ehci-pci
[ 19.159483] usb 2-3: device not accepting address 31, error -71
[ 19.262490] usb 2-3: new high-speed USB device number 32 using ehci-pci
[ 19.726487] usb 2-3: device not accepting address 32, error -71
[ 19.829500] usb 2-3: new high-speed USB device number 33 using ehci-pci
[ 20.027490] usb 2-3: device descriptor read/64, error -71
[ 20.325490] usb 2-3: device descriptor read/64, error -71
[ 20.529489] usb 2-3: new high-speed USB device number 34 using ehci-pci
[ 20.727490] usb 2-3: device descriptor read/64, error -71
[ 21.025490] usb 2-3: device descriptor read/64, error -71
[ 21.340490] usb 2-3: new high-speed USB device number 35 using ehci-pci
[ 21.804487] usb 2-3: device not accepting address 35, error -71
[ 21.907490] usb 2-3: new high-speed USB device number 36 using ehci-pci
[ 22.371487] usb 2-3: device not accepting address 36, error -71
[ 22.474489] usb 2-3: new high-speed USB device number 37 using ehci-pci
[ 22.672489] usb 2-3: device descriptor read/64, error -71
[ 22.970495] usb 2-3: device descriptor read/64, error -71
[ 23.174439] usb 2-3: new high-speed USB device number 38 using ehci-pci
[ 23.372489] usb 2-3: device descriptor read/64, error -71
[ 23.670489] usb 2-3: device descriptor read/64, error -71
[ 23.985494] usb 2-3: new high-speed USB device number 39 using ehci-pci
[ 24.449426] usb 2-3: device not accepting address 39, error -71
[ 24.552487] usb 2-3: new high-speed USB device number 40 using ehci-pci
[ 25.016490] usb 2-3: device not accepting address 40, error -71
[ 25.119430] usb 2-3: new high-speed USB device number 41 using ehci-pci
[ 25.317489] usb 2-3: device descriptor read/64, error -71
[ 25.615488] usb 2-3: device descriptor read/64, error -71
[ 25.819499] usb 2-3: new high-speed USB device number 42 using ehci-pci
[ 26.017488] usb 2-3: device descriptor read/64, error -71
[ 26.315488] usb 2-3: device descriptor read/64, error -71
[ 26.630488] usb 2-3: new high-speed USB device number 43 using ehci-pci
[ 27.094423] usb 2-3: device not accepting address 43, error -71
[ 27.197431] usb 2-3: new high-speed USB device number 44 using ehci-pci
[ 27.661487] usb 2-3: device not accepting address 44, error -71
[ 27.764487] usb 2-3: new high-speed USB device number 45 using ehci-pci
[ 27.962493] usb 2-3: device descriptor read/64, error -71
[ 28.260488] usb 2-3: device descriptor read/64, error -71
[ 28.464489] usb 2-3: new high-speed USB device number 46 using ehci-pci
[ 28.849439] usb 2-3: new high-speed USB device number 47 using ehci-pci
[ 29.313426] usb 2-3: device not accepting address 47, error -71
[ 29.416429] usb 2-3: new high-speed USB device number 48 using ehci-pci
[ 29.880491] usb 2-3: device not accepting address 48, error -71
[ 29.983493] usb 2-3: new high-speed USB device number 49 using ehci-pci
[ 30.181487] usb 2-3: device descriptor read/64, error -71
[ 30.479487] usb 2-3: device descriptor read/64, error -71
[ 30.683488] usb 2-3: new high-speed USB device number 50 using ehci-pci
[ 30.881493] usb 2-3: device descriptor read/64, error -71
[ 31.179489] usb 2-3: device descriptor read/64, error -71
[ 31.494488] usb 2-3: new high-speed USB device number 51 using ehci-pci
[ 31.958490] usb 2-3: device not accepting address 51, error -71
[ 32.061491] usb 2-3: new high-speed USB device number 52 using ehci-pci
[ 32.525483] usb 2-3: device not accepting address 52, error -71
[ 32.629509] usb 2-3: new high-speed USB device number 53 using ehci-pci
[ 32.827519] usb 2-3: device descriptor read/64, error -71
[ 33.126436] usb 2-3: device descriptor read/64, error -71
[ 33.330496] usb 2-3: new high-speed USB device number 54 using ehci-pci
[ 33.715491] usb 2-3: new high-speed USB device number 55 using ehci-pci
[ 34.179487] usb 2-3: device not accepting address 55, error -71
[ 34.282492] usb 2-3: new high-speed USB device number 56 using ehci-pci
[ 34.746487] usb 2-3: device not accepting address 56, error -71
[ 34.849443] usb 2-3: new high-speed USB device number 57 using ehci-pci
[ 35.047431] usb 2-3: device descriptor read/64, error -71
[ 35.345490] usb 2-3: device descriptor read/64, error -71
[ 35.549491] usb 2-3: new high-speed USB device number 58 using ehci-pci
[ 35.747490] usb 2-3: device descriptor read/64, error -71
[ 36.045430] usb 2-3: device descriptor read/64, error -71
[ 36.360490] usb 2-3: new high-speed USB device number 59 using ehci-pci
[ 36.824506] usb 2-3: device not accepting address 59, error -71
[ 36.928494] usb 2-3: new high-speed USB device number 60 using ehci-pci
[ 37.392487] usb 2-3: device not accepting address 60, error -71
[ 37.495491] usb 2-3: new high-speed USB device number 61 using ehci-pci
[ 37.693490] usb 2-3: device descriptor read/64, error -71
[ 37.991509] usb 2-3: device descriptor read/64, error -71
[ 38.195493] usb 2-3: new high-speed USB device number 62 using ehci-pci
[ 38.393488] usb 2-3: device descriptor read/64, error -71
[ 38.691487] usb 2-3: device descriptor read/64, error -71
[ 39.006432] usb 2-3: new high-speed USB device number 63 using ehci-pci
[ 39.470486] usb 2-3: device not accepting address 63, error -71
[ 39.573488] usb 2-3: new high-speed USB device number 64 using ehci-pci
[ 40.037514] usb 2-3: device not accepting address 64, error -71
[ 40.140431] usb 2-3: new high-speed USB device number 65 using ehci-pci
[ 40.338487] usb 2-3: device descriptor read/64, error -71
[ 40.636488] usb 2-3: device descriptor read/64, error -71
[ 40.840514] usb 2-3: new high-speed USB device number 66 using ehci-pci
[ 41.038487] usb 2-3: device descriptor read/64, error -71
[ 41.336488] usb 2-3: device descriptor read/64, error -71
[ 41.651428] usb 2-3: new high-speed USB device number 67 using ehci-pci
[ 42.115485] usb 2-3: device not accepting address 67, error -71
[ 42.218487] usb 2-3: new high-speed USB device number 68 using ehci-pci
[ 42.682483] usb 2-3: device not accepting address 68, error -71
[ 42.785487] usb 2-3: new high-speed USB device number 69 using ehci-pci
[ 42.983513] usb 2-3: device descriptor read/64, error -71
[ 43.468487] usb 2-3: new high-speed USB device number 70 using ehci-pci
[ 43.932510] usb 2-3: device not accepting address 70, error -71
[ 44.036490] usb 2-3: new high-speed USB device number 71 using ehci-pci
[ 44.500485] usb 2-3: device not accepting address 71, error -71
[ 44.604427] usb 2-3: new high-speed USB device number 72 using ehci-pci
[ 44.802487] usb 2-3: device descriptor read/64, error -71
[ 45.101427] usb 2-3: device descriptor read/64, error -71
[ 45.305487] usb 2-3: new high-speed USB device number 73 using ehci-pci
[ 45.503486] usb 2-3: device descriptor read/64, error -71
[ 45.801487] usb 2-3: device descriptor read/64, error -71
[ 46.116489] usb 2-3: new high-speed USB device number 74 using ehci-pci
[ 46.580486] usb 2-3: device not accepting address 74, error -71
[ 46.684488] usb 2-3: new high-speed USB device number 75 using ehci-pci
[ 47.148485] usb 2-3: device not accepting address 75, error -71
[ 47.252428] usb 2-3: new high-speed USB device number 76 using ehci-pci
[ 47.450427] usb 2-3: device descriptor read/64, error -71
[ 47.748487] usb 2-3: device descriptor read/64, error -71
[ 47.952492] usb 2-3: new high-speed USB device number 77 using ehci-pci
[ 48.150431] usb 2-3: device descriptor read/64, error -71
[ 48.448428] usb 2-3: device descriptor read/64, error -71
[ 48.763487] usb 2-3: new high-speed USB device number 78 using ehci-pci
[ 49.227485] usb 2-3: device not accepting address 78, error -71
[ 49.331488] usb 2-3: new high-speed USB device number 79 using ehci-pci
[ 49.795485] usb 2-3: device not accepting address 79, error -71
[ 49.899494] usb 2-3: new high-speed USB device number 80 using ehci-pci
[ 50.097427] usb 2-3: device descriptor read/64, error -71
[ 50.395487] usb 2-3: device descriptor read/64, error -71
[ 50.599427] usb 2-3: new high-speed USB device number 81 using ehci-pci
[ 50.797487] usb 2-3: device descriptor read/64, error -71
[ 51.095425] usb 2-3: device descriptor read/64, error -71
[ 51.410488] usb 2-3: new high-speed USB device number 82 using ehci-pci
[ 51.874509] usb 2-3: device not accepting address 82, error -71
[ 51.977490] usb 2-3: new high-speed USB device number 83 using ehci-pci
[ 52.441489] usb 2-3: device not accepting address 83, error -71
[ 52.544488] usb 2-3: new high-speed USB device number 84 using ehci-pci
[ 52.742487] usb 2-3: device descriptor read/64, error -71
[ 53.040488] usb 2-3: device descriptor read/64, error -71
[ 53.244428] usb 2-3: new high-speed USB device number 85 using ehci-pci
[ 53.442428] usb 2-3: device descriptor read/64, error -71
[ 53.740487] usb 2-3: device descriptor read/64, error -71
[ 54.055491] usb 2-3: new high-speed USB device number 86 using ehci-pci
[ 54.519486] usb 2-3: device not accepting address 86, error -71
[ 54.622487] usb 2-3: new high-speed USB device number 87 using ehci-pci
[ 55.086486] usb 2-3: device not accepting address 87, error -71
[ 55.189489] usb 2-3: new high-speed USB device number 88 using ehci-pci
[ 55.387428] usb 2-3: device descriptor read/64, error -71
[ 55.685487] usb 2-3: device descriptor read/64, error -71
[ 55.889494] usb 2-3: new high-speed USB device number 89 using ehci-pci
[ 56.087487] usb 2-3: device descriptor read/64, error -71
[ 56.385487] usb 2-3: device descriptor read/64, error -71
[ 56.700488] usb 2-3: new high-speed USB device number 90 using ehci-pci
[ 57.164484] usb 2-3: device not accepting address 90, error -71
[ 57.267487] usb 2-3: new high-speed USB device number 91 using ehci-pci
[ 57.731486] usb 2-3: device not accepting address 91, error -71
[ 57.834503] usb 2-3: new high-speed USB device number 92 using ehci-pci
[ 58.032488] usb 2-3: device descriptor read/64, error -71
[ 58.330488] usb 2-3: device descriptor read/64, error -71
[ 58.534487] usb 2-3: new high-speed USB device number 93 using ehci-pci
[ 58.732488] usb 2-3: device descriptor read/64, error -71
[ 59.030487] usb 2-3: device descriptor read/64, error -71
[ 59.345487] usb 2-3: new high-speed USB device number 94 using ehci-pci
[ 59.809485] usb 2-3: device not accepting address 94, error -71
[ 59.912495] usb 2-3: new high-speed USB device number 95 using ehci-pci
[ 60.376485] usb 2-3: device not accepting address 95, error -71
[ 60.479488] usb 2-3: new high-speed USB device number 96 using ehci-pci
[ 60.677487] usb 2-3: device descriptor read/64, error -71
[ 60.975510] usb 2-3: device descriptor read/64, error -71
[ 61.179492] usb 2-3: new high-speed USB device number 97 using ehci-pci
[ 61.377487] usb 2-3: device descriptor read/64, error -71
[ 61.675487] usb 2-3: device descriptor read/64, error -71
[ 61.990491] usb 2-3: new high-speed USB device number 98 using ehci-pci
[ 62.454426] usb 2-3: device not accepting address 98, error -71
[ 62.557429] usb 2-3: new high-speed USB device number 99 using ehci-pci
[ 63.021389] usb 2-3: device not accepting address 99, error -71
[ 63.124442] usb 2-3: new high-speed USB device number 100 using ehci-pci
[ 63.322436] usb 2-3: device descriptor read/64, error -71
[ 63.812447] usb 2-3: new high-speed USB device number 101 using ehci-pci
[ 64.277386] usb 2-3: device not accepting address 101, error -71
[ 64.381450] usb 2-3: new high-speed USB device number 102 using ehci-pci
[ 64.846392] usb 2-3: device not accepting address 102, error -71
[ 64.950413] usb 2-3: new high-speed USB device number 103 using ehci-pci
[ 65.336443] usb 2-3: new high-speed USB device number 104 using ehci-pci
[ 65.801433] usb 2-3: device not accepting address 104, error -71
[ 65.905441] usb 2-3: new high-speed USB device number 105 using ehci-pci
[ 66.370393] usb 2-3: device not accepting address 105, error -71
[ 66.473452] usb 2-3: new high-speed USB device number 106 using ehci-pci
[ 66.671442] usb 2-3: device descriptor read/64, error -71
[ 66.969454] usb 2-3: device descriptor read/64, error -71
[ 67.173448] usb 2-3: new high-speed USB device number 107 using ehci-pci
[ 67.371427] usb 2-3: device descriptor read/64, error -71
[ 67.670453] usb 2-3: device descriptor read/64, error -71
[ 68.095468] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 68.121460] usb 4-3: not running at top speed; connect to a high speed hub
[ 68.137466] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 68.142351] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 68.147203] usb 4-3: Product: Flash Disk
[ 68.152046] usb 4-3: Manufacturer: USB
[ 68.961468] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 68.961571] scsi8 : usb-storage 4-3:1.0
[ 68.961654] usbcore: registered new interface driver usb-storage
<TEST-4>
...
[ 1.033684] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.499601] usb 2-3: device not accepting address 2, error -71
[ 1.602668] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 2.068641] usb 2-3: device not accepting address 3, error -71
[ 2.172667] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.557715] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.021635] usb 2-3: device not accepting address 5, error -71
[ 3.125700] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.589698] usb 2-3: device not accepting address 6, error -71
[ 3.693700] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 3.891738] usb 2-3: device descriptor read/64, error -71
[ 4.190699] usb 2-3: device descriptor read/64, error -71
[ 4.394701] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 4.592699] usb 2-3: device descriptor read/64, error -71
[ 4.890730] usb 2-3: device descriptor read/64, error -71
[ 5.312652] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 5.336649] usb 4-3: not running at top speed; connect to a high speed hub
[ 5.352651] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 5.354759] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 5.356806] usb 4-3: Product: Flash Disk
[ 5.358784] usb 4-3: Manufacturer: USB
[ 5.365300] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 5.367324] scsi8 : usb-storage 4-3:1.0
[ 5.369328] usbcore: registered new interface driver usb-storage
~~~~~~~~~~~~~~
$ cat /sys/module/usbcore/parameters/old_scheme_first
Y
$ cat /sys/module/usbcore/parameters/initial_descriptor_timeout
0
...
[ 0.000000] Kernel command line: ... usbcore.old_scheme_first=1
usbcore.initial_descriptor_timeout=0 ...
<TEST-5>
...
[ 1.030395] usb 2-3: new high-speed USB device number 2 using ehci-pci
[ 1.492398] usb 2-3: device not accepting address 2, error -71
[ 1.594621] usb 2-3: new high-speed USB device number 3 using ehci-pci
[ 2.061409] usb 2-3: device not accepting address 3, error -71
[ 2.165425] usb 2-3: new high-speed USB device number 4 using ehci-pci
[ 2.364408] usb 2-3: device descriptor read/64, error -71
[ 2.850470] usb 2-3: new high-speed USB device number 5 using ehci-pci
[ 3.315396] usb 2-3: device not accepting address 5, error -71
[ 3.419402] usb 2-3: new high-speed USB device number 6 using ehci-pci
[ 3.884411] usb 2-3: device not accepting address 6, error -71
[ 3.988403] usb 2-3: new high-speed USB device number 7 using ehci-pci
[ 4.187390] usb 2-3: device descriptor read/64, error -71
[ 4.486361] usb 2-3: device descriptor read/64, error -71
[ 4.691362] usb 2-3: new high-speed USB device number 8 using ehci-pci
[ 4.890362] usb 2-3: device descriptor read/64, error -71
[ 5.376389] usb 2-3: new high-speed USB device number 9 using ehci-pci
[ 5.841462] usb 2-3: device not accepting address 9, error -71
[ 5.945463] usb 2-3: new high-speed USB device number 10 using ehci-pci
[ 6.410382] usb 2-3: device not accepting address 10, error -71
[ 6.514399] usb 2-3: new high-speed USB device number 11 using ehci-pci
[ 6.713375] usb 2-3: device descriptor read/64, error -71
[ 7.012404] usb 2-3: device descriptor read/64, error -71
[ 7.217399] usb 2-3: new high-speed USB device number 12 using ehci-pci
[ 7.603394] usb 2-3: new high-speed USB device number 13 using ehci-pci
[ 8.068395] usb 2-3: device not accepting address 13, error -71
[ 8.172371] usb 2-3: new high-speed USB device number 14 using ehci-pci
[ 8.637382] usb 2-3: device not accepting address 14, error -71
[ 8.741361] usb 2-3: new high-speed USB device number 15 using ehci-pci
[ 9.202394] usb 4-3: new full-speed USB device number 2 using ohci-pci
[ 9.226427] usb 4-3: not running at top speed; connect to a high speed hub
[ 9.241429] usb 4-3: New USB device found, idVendor=0ea0, idProduct=2168
[ 9.243364] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 9.245300] usb 4-3: Product: Flash Disk
[ 9.247195] usb 4-3: Manufacturer: USB
[ 9.253073] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 9.255097] scsi8 : usb-storage 4-3:1.0
[ 9.257061] usbcore: registered new interface driver usb-storage
~~~~~~~~~~~~~~
~~~~~~~~~~~~~~
https://bugzilla.redhat.com/show_bug.cgi?id=1096786
Unplug the device without unmounting,
...
usb 2-1: USB disconnect, device number 2
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4692 at fs/sysfs/group.c:216 sysfs_remove_group+0x93/0xa0()
sysfs group ffffffff81cb1300 not found for kobject 'target8:0:0'
CPU: 0 PID: 4692 Comm: umount Not tainted 3.14.3-200.fc20.x86_64 #1
Call Trace:
[<ffffffff816ef242>] dump_stack+0x45/0x56
[<ffffffff8108a1bd>] warn_slowpath_common+0x7d/0xa0
[<ffffffff8108a23c>] warn_slowpath_fmt+0x5c/0x80
[<ffffffff81265598>] ? kernfs_find_and_get_ns+0x48/0x60
[<ffffffff81264233>] sysfs_remove_group+0x93/0xa0
[<ffffffff8146b543>] dpm_sysfs_remove+0x43/0x50
[<ffffffff81460b35>] device_del+0x45/0x1c0
[<ffffffff8148deb7>] scsi_target_reap_usercontext+0x27/0x40
[<ffffffff810a4e67>] execute_in_process_context+0x67/0x70
[<ffffffff8148f334>] scsi_target_reap+0xc4/0xf0
[<ffffffff81491366>] scsi_device_dev_release_usercontext+0xe6/0x120
[<ffffffff810a4e67>] execute_in_process_context+0x67/0x70
[<ffffffff8149127c>] scsi_device_dev_release+0x1c/0x20
[<ffffffff814600e2>] device_release+0x32/0xa0
[<ffffffff813560a7>] kobject_cleanup+0x77/0x1b0
[<ffffffff81355f60>] kobject_put+0x30/0x60
[<ffffffff81460407>] put_device+0x17/0x20
[<ffffffff8148268b>] scsi_device_put+0x3b/0x50
[<ffffffff81495e50>] scsi_disk_put+0x30/0x50
[<ffffffff814961b2>] sd_release+0x42/0xd0
[<ffffffff8122489c>] __blkdev_put+0x16c/0x1a0
[<ffffffff8122483e>] __blkdev_put+0x10e/0x1a0
[<ffffffff8122521c>] blkdev_put+0x4c/0x120
[<ffffffff811ebd64>] kill_block_super+0x44/0x70
[<ffffffff811ec06d>] deactivate_locked_super+0x3d/0x60
[<ffffffff811ec636>] deactivate_super+0x46/0x60
[<ffffffff81208dac>] mntput_no_expire+0xac/0x140
[<ffffffff8120a37d>] SyS_umount+0x9d/0x110
[<ffffffff816ff5e9>] system_call_fastpath+0x16/0x1b
---[ end trace 6a4cda17930756e9 ]---
BTW 3.15.0-0.rc5.git0.1.fc21.x86_64 doesn't have this bug.
poma