利用ds5+dstream将这个工程代码烧录到指定的目标板中，全程运行后再将目标板的USB端口连接到Linux主机上，USB枚举过程时而成功，时而失败，以下是将USB端口接到Linux主机后再终端上打印的信息：
成功的信息：
[ 4020.340130] usb 2-4: new high-speed USB device number 12 usingehci-pci[ 4020.735645] usb 2-4: config 1 interface 0 altsetting 0 endpoint0x84 has an invalid bInterval 255, changing to 11[ 4020.735653] usb 2-4: config 1 interface 1 altsetting 0 bulkendpoint 0x1 has invalid maxpacket 64[ 4020.735658] usb 2-4: config 1 interface 1 altsetting 0 bulkendpoint 0x82 has invalid maxpacket 64[ 4021.066894] usb 2-4: New USB device found, idVendor=8484,idProduct=0100[ 4021.066905] usb 2-4: New USB device strings: Mfr=1, Product=2,SerialNumber=3[ 4021.066908] usb 2-4: Product: EL Composite device[ 4021.066911] usb 2-4: Manufacturer: Expres Logic[ 4021.066913] usb 2-4: SerialNumber: 0001[ 4021.150016] cdc_acm 2-4:1.0: ttyACM0: USB ACM device[ 4036.160400] cdc_acm 2-4:1.0: failed to set dtr/rts[ 4061.000424] cdc_acm 2-4:1.0: failed to set dtr/rts疑惑：最后为什么打印“cdc_acm 2-4:1.0: failed to set dtr/rts”呢？？？失败信息：[37479.512130] usb 2-3: new high-speed USB device number 15 usingehci-pci[37479.904168] usb 7-1: new full-speed USB device number 10 usinguhci_hcd[37485.016173] usb 7-1: device descriptor read/64, error -110[37500.232168] usb 7-1: device descriptor read/64, error -110[37500.448129] usb 7-1: new full-speed USB device number 11 usinguhci_hcd[37505.560169] usb 7-1: device descriptor read/64, error -110[37520.776174] usb 7-1: device descriptor read/64, error -110[37520.992155] usb 7-1: new full-speed USB device number 12 usinguhci_hcd[37531.400166] usb 7-1: device not accepting address 12, error -110[37531.512162] usb 7-1: new full-speed USB device number 13 usinguhci_hcd[37541.920165] usb 7-1: device not accepting address 13, error -110[37541.920218]usb usb7-port1: unable to enumerate USB device以上是枚举的结果，想请教高手为什么会有这种不稳定的现象，又该如何去定位找错？谢谢！

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