nfs 挂载android rootfs ，挂载nfs 根文件系统到一半总是出现usb hub断开的情况，就是fe1.1s断开，导致网络无法连接，因为dm9621是usb网卡，挂在fe1.1s上。后来又重新连接上，但是系统挂载NFS文件系统就出问题。不知道是驱动问题还是硬件问题？请客服给个解释
下面是启动信息：
[ 3.465000] Bluetooth: RFCOMM ver 1.11
[ 3.470000] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 3.475000] Bluetooth: BNEP filters: protocol multicast
[ 3.480000] usb 1-1: new high-speed USB device number 3 using s5p-ehci
[ 3.490000] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
[ 3.495000] NET: Registered protocol family 35
[ 3.500000] EXYNOS4X12: Adaptive Support Voltage init
[ 3.505000] EXYNOS4X12(SG): ORIG : 2 MOD : 0 RESULT : 2
[ 3.510000] EXYNOS: Fail to get HPM Value
[ 3.515000] VFP support v0.3: implementor 41 architecture 3 part 30 variant 4
[ 3.520000] ThumbEE CPU extension supported.
[ 3.525000] Registering SWP/SWPB emulation handler
[ 3.530000] [ 6 ] Memory Type Undertermined.
[ 3.535000] DVFS : VDD_INT Voltage table set with 0 Group
[ 3.565000] Failed to init busfreq.
[ 3.565000] s3c-rtc s3c64xx-rtc: setting system clock to 2014-07-03 02:06:23)
[ 3.610000] usb 1-1: New USB device found, idVendor=1a40, idProduct=0101
[ 3.610000] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ 3.610000] usb 1-1: Product: USB 2.0 Hub
[ 3.610000] hub 1-1:1.0: USB hub found
[ 3.610000] hub 1-1:1.0: 4 ports detected
[ 3.880000] usb 1-1.4: new full-speed USB device number 4 using s5p-ehci
[ 3.970000] usb 1-1.4: not running at top speed; connect to a high speed hub
[ 4.045000] usb 1-1.4: New USB device found, idVendor=0a46, idProduct=9621
[ 4.045000] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumbe3
[ 4.045000] dm962x: dm_read_reg() 0x29 0x0a
[ 4.045000] dm962x: dm_read_reg() 0x28 0x46
[ 4.045000] dm962x: dm_read_reg() 0x2b 0x96
[ 4.045000] dm962x: dm_read_reg() 0x2a 0x21
[ 4.050000] dm962x: dm_read_reg() 0xF2 0x00
[ 4.055000] dm962x: [Analysis.2] 0xF2, D[7] 0 OK
[ 4.060000] dm962x: [Analysis.2] 0xF2, D[6] 0 OK
[ 4.065000] dm962x: [Analysis.2] 0xF2, D[5] 0 EP1: Empty
[ 4.070000] dm962x: [Analysis.2] 0xF2, D[3] 0 OK
[ 4.075000] dm962x: [Analysis.2] 0xF2, D[2] 0 OK
[ 4.080000] dm962x: [Analysis.2] 0xF2, D[1] 0 OK
[ 4.085000] dm962x: [Analysis.2] 0xF2, D[0] 0 Status: TX buffer 0 pkts
[ 4.095000] dm962x: ethernet MAC address 00:00:ff:ff:00:00 (chip)
[ 4.100000] dm962x: 9620 Mode = 128
[ 4.115000] dm9620 1-1.4:1.0: eth0: register 'dm9620' at usb-s5p-ehci-1.4, D0
[ 4.575000] dm9620 1-1.4:1.0: eth0: link down
[ 4.585000] link_reset() speed: 10 duplex: 0
[ 4.590000] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 5.795000] Link Status is: 1
[ 5.800000] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 5.800000] dm9620 1-1.4:1.0: eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
[ 5.815000] IP-Config: Complete:
[ 5.815000] device=eth0, addr=192.168.1.115, mask=255.255.255.0, gw=1924
[ 5.815000] host=192.168.1.115, domain=, nis-domain=(none)
[ 5.815000] bootserver=192.168.1.114, rootserver=192.168.1.114, rootpat=
[ 5.815000] hotplug_policy_init: intialised with policy : DVFS_NR_BASED_HOTPG
[ 5.820000] ALSA device list:
[ 5.830000] No soundcards found.
[ 5.830000] link_reset() speed: 10 duplex: 0
[ 5.895000] VFS: Mounted root (nfs filesystem) on device 0:10.
[ 5.895000] Freeing init memory: 200K
[ 6.270000] usb 1-1: USB disconnect, device number 3
[ 6.270000] usb 1-1.4: USB disconnect, device number 4
[ 6.270000] EXT4-fs (mmcblk0p2): VFS: Can't find ext4 filesystem
[ 6.270000] dm9620 1-1.4:1.0: eth0: unregister 'dm9620' usb-s5p-ehci-1.4, Dat
[ 6.315000] fs_mgr: Cannot mount filesystem on /dev/block/mmcblk0p2 at /systm
[ 6.315000] init: fs_mgr_mount_all returned an error
[ 6.355000] dm9620_unbind():
[ 6.355000] flag_fail_count 0
[ 6.355000] rx_length_errors 0
[ 6.355000] rx_over_errors 0
[ 6.355000] rx_crc_errors 0
[ 6.355000] rx_frame_errors 0
[ 6.355000] rx_fifo_errors 0
[ 6.355000] rx_missed_errors 0
[ 6.585000] usb 1-1: new high-speed USB device number 5 using s5p-ehci
[ 6.715000] usb 1-1: New USB device found, idVendor=1a40, idProduct=0101
[ 6.715000] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ 6.715000] usb 1-1: Product: USB 2.0 Hub
[ 6.715000] hub 1-1:1.0: USB hub found
[ 6.715000] hub 1-1:1.0: 4 ports detected
[ 6.990000] usb 1-1.4: new full-speed USB device number 6 using s5p-ehci
[ 7.080000] usb 1-1.4: not running at top speed; connect to a high speed hub
[ 7.155000] usb 1-1.4: New USB device found, idVendor=0a46, idProduct=9621
[ 7.155000] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumbe3
[ 7.155000] dm962x: dm_read_reg() 0x29 0x0a
[ 7.155000] dm962x: dm_read_reg() 0x28 0x46
[ 7.155000] dm962x: dm_read_reg() 0x2b 0x96
[ 7.155000] dm962x: dm_read_reg() 0x2a 0x21
[ 7.160000] dm962x: dm_read_reg() 0xF2 0x00
[ 7.165000] dm962x: [Analysis.2] 0xF2, D[7] 0 OK
[ 7.170000] dm962x: [Analysis.2] 0xF2, D[6] 0 OK
[ 7.175000] dm962x: [Analysis.2] 0xF2, D[5] 0 EP1: Empty
[ 7.180000] dm962x: [Analysis.2] 0xF2, D[3] 0 OK
[ 7.185000] dm962x: [Analysis.2] 0xF2, D[2] 0 OK
[ 7.190000] dm962x: [Analysis.2] 0xF2, D[1] 0 OK
[ 7.195000] dm962x: [Analysis.2] 0xF2, D[0] 0 Status: TX buffer 0 pkts
[ 7.205000] dm962x: ethernet MAC address 00:00:ff:ff:00:00 (chip)
[ 7.205000] dm962x: 9620 Mode = 128
[ 7.225000] dm9620 1-1.4:1.0: eth0: register 'dm9620' at usb-s5p-ehci-1.4, D0
[ 15.340000] nfs: server 192.168.1.114 not responding, still trying
[ 27.355000] usb 1-1: USB disconnect, device number 5
[ 27.355000] usb 1-1.4: USB disconnect, device number 6
[ 27.355000] dm9620 1-1.4:1.0: eth0: unregister 'dm9620' usb-s5p-ehci-1.4, Dat
[ 27.370000] dm9620_unbind():
[ 27.370000] flag_fail_count 0
[ 27.370000] rx_length_errors 0
[ 27.370000] rx_over_errors 0
[ 27.370000] rx_crc_errors 0
[ 27.370000] rx_frame_errors 0
[ 27.370000] rx_fifo_errors 0
[ 27.375000] rx_missed_errors 0
[ 27.610000] usb 1-1: new high-speed USB device number 7 using s5p-ehci
[ 27.740000] usb 1-1: New USB device found, idVendor=1a40, idProduct=0101
[ 27.740000] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ 27.740000] usb 1-1: Product: USB 2.0 Hub
[ 27.740000] hub 1-1:1.0: USB hub found
[ 27.740000] hub 1-1:1.0: 4 ports detected
[ 28.015000] usb 1-1.4: new full-speed USB device number 8 using s5p-ehci
[ 28.105000] usb 1-1.4: not running at top speed; connect to a high speed hub
[ 28.180000] usb 1-1.4: New USB device found, idVendor=0a46, idProduct=9621
[ 28.180000] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumbe3
[ 28.180000] dm962x: dm_read_reg() 0x29 0x0a
[ 28.180000] dm962x: dm_read_reg() 0x28 0x46
[ 28.180000] dm962x: dm_read_reg() 0x2b 0x96
[ 28.180000] dm962x: dm_read_reg() 0x2a 0x21
[ 28.185000] dm962x: dm_read_reg() 0xF2 0x20
[ 28.190000] dm962x: [Analysis.2] 0xF2, D[7] 0 OK
[ 28.195000] dm962x: [Analysis.2] 0xF2, D[6] 0 OK
[ 28.200000] dm962x: [Analysis.2] 0xF2, D[5] 1 EP1: Data Ready
[ 28.205000] dm962x: [Analysis.2] 0xF2, D[3] 0 OK
[ 28.210000] dm962x: [Analysis.2] 0xF2, D[2] 0 OK
[ 28.215000] dm962x: [Analysis.2] 0xF2, D[1] 0 OK
[ 28.220000] dm962x: [Analysis.2] 0xF2, D[0] 0 Status: TX buffer 0 pkts
[ 28.235000] dm962x: ethernet MAC address 00:00:ff:ff:00:00 (chip)
[ 28.235000] dm962x: 9620 Mode = 128
[ 28.255000] dm9620 1-1.4:1.0: eth0: register 'dm9620' at usb-s5p-ehci-1.4, D0
[ 62.340000] usb 1-1: USB disconnect, device number 7
[ 62.340000] usb 1-1.4: USB disconnect, device number 8
[ 62.340000] dm9620 1-1.4:1.0: eth0: unregister 'dm9620' usb-s5p-ehci-1.4, Dat
[ 62.375000] dm9620_unbind():
[ 62.375000] flag_fail_count 0
[ 62.375000] rx_length_errors 0
[ 62.375000] rx_over_errors 0
[ 62.375000] rx_crc_errors 0
[ 62.375000] rx_frame_errors 0
[ 62.375000] rx_fifo_errors 0
[ 62.375000] rx_missed_errors 0
[ 62.605000] usb 1-1: new high-speed USB device number 9 using s5p-ehci
[ 62.735000] usb 1-1: New USB device found, idVendor=1a40, idProduct=0101
[ 62.735000] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ 62.735000] usb 1-1: Product: USB 2.0 Hub
[ 62.735000] hub 1-1:1.0: USB hub found
[ 62.735000] hub 1-1:1.0: 4 ports detected
[ 63.010000] usb 1-1.4: new full-speed USB device number 10 using s5p-ehci
[ 63.100000] usb 1-1.4: not running at top speed; connect to a high speed hub
[ 63.175000] usb 1-1.4: New USB device found, idVendor=0a46, idProduct=9621
[ 63.175000] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumbe3
[ 63.175000] dm962x: dm_read_reg() 0x29 0x0a
[ 63.175000] dm962x: dm_read_reg() 0x28 0x46
[ 63.175000] dm962x: dm_read_reg() 0x2b 0x96
[ 63.175000] dm962x: dm_read_reg() 0x2a 0x21
[ 63.180000] dm962x: dm_read_reg() 0xF2 0x20
[ 63.185000] dm962x: [Analysis.2] 0xF2, D[7] 0 OK
[ 63.190000] dm962x: [Analysis.2] 0xF2, D[6] 0 OK
[ 63.195000] dm962x: [Analysis.2] 0xF2, D[5] 1 EP1: Data Ready
[ 63.200000] dm962x: [Analysis.2] 0xF2, D[3] 0 OK
[ 63.205000] dm962x: [Analysis.2] 0xF2, D[2] 0 OK
[ 63.210000] dm962x: [Analysis.2] 0xF2, D[1] 0 OK
[ 63.215000] dm962x: [Analysis.2] 0xF2, D[0] 0 Status: TX buffer 0 pkts
[ 63.225000] dm962x: ethernet MAC address 00:00:ff:ff:00:00 (chip)
[ 63.230000] dm962x: 9620 Mode = 128
[ 63.245000] dm9620 1-1.4:1.0: eth0: register 'dm9620' at usb-s5p-ehci-1.4, D0
