[ 733.154747] Using Buffer DMA mode
[ 733.154766] Periodic Transfer Interrupt Enhancement - disabled
[ 733.154774] Multiprocessor Interrupt Enhancement - disabled
[ 733.154782] OTG VER PARAM: 0, OTG VER FLAG: 0
[ 733.154789] ^^^^^^^^^^^^^^^^^^Host Mode
[ 733.199026] Init: Power Port (0)
[ 733.483952] Indeed it is in host mode hprt0 = 00021501
[ 733.661048] usb 3-1: new high-speed USB device number 18 using usb20_host
[ 734.074185] usb 3-1: device not accepting address 18, error -71
[ 734.074511] Indeed it is in host mode hprt0 = 00001101
[ 734.251426] usb 3-1: new high-speed USB device number 19 using usb20_host
[ 739.378141] NYET/NAK/ACK/other in non-error case, 0x00000002
[ 744.504712] usb 3-1: device not accepting address 19, error -110
[ 744.505022] Indeed it is in host mode hprt0 = 00001501
[ 744.681754] usb 3-1: new high-speed USB device number 20 using usb20_host
[ 744.683712] Indeed it is in host mode hprt0 = 00001101
[ 744.858881] usb 3-1: device descriptor read/64, error -71
[ 744.968965] Indeed it is in host mode hprt0 = 00001101
[ 745.144341] usb 3-1: device descriptor read/64, error -71
[ 745.252555] Indeed it is in host mode hprt0 = 00001101
[ 745.429708] usb 3-1: new high-speed USB device number 21 using usb20_host
[ 750.349798] NYET/NAK/ACK/other in non-error case, 0x00000002
[ 755.269850] NYET/NAK/ACK/other in non-error case, 0x00000002
[ 760.189702] Indeed it is in host mode hprt0 = 00001501
[ 760.366800] usb 3-1: device descriptor read/64, error -110
[ 760.476061] Indeed it is in host mode hprt0 = 00001101
[ 760.652156] usb 3-1: device descriptor read/64, error -71
[ 760.760403] hub 3-0:1.0: unable to enumerate USB device on port 1
问题已解决。
static void compute_isochronous_actual_length(struct urb *urb)
{
unsigned int i;
if (urb->number_of_packets > 0) {
urb->actual_length = 0;
for (i = 0; i < urb->number_of_packets; i++)
urb->actual_length +=
urb->iso_frame_desc[i].actual_length;
}