我在 ubuntu 上安装了 realtek SD 卡读卡器，但是出现了一些奇怪的情况：有时候能识别 SD 卡，有时候把卡放进去之后没有任何反应，有时候会显示，然后消失，然后又显示，然后又消失等等，出现这种情况时的 dmesg 如下：
[ 705.838650] usb 1-1.2: new high-speed USB device number 4 using ehci_hcd
[ 706.414218] usb 1-1.2: device not accepting address 4, error -71
[ 706.430772] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 707.633972] usb 1-1.2: new high-speed USB device number 6 using ehci_hcd
[ 707.662063] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 707.831366] ieee80211 phy0: START: tid 1 is not agg'able
[ 707.889873] usb 1-1.2: new high-speed USB device number 7 using ehci_hcd
[ 707.918216] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 708.209589] usb 1-1.2: new high-speed USB device number 8 using ehci_hcd
[ 708.400918] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 708.400923] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 708.400927] usb 1-1.2: Product: USB2.0-CRW
[ 708.400930] usb 1-1.2: Manufacturer: Generic
[ 708.400934] usb 1-1.2: SerialNumber: 20071114173400000
[ 708.465062] Initializing USB Mass Storage driver...
[ 708.465154] usbcore: registered new interface driver usb-storage
[ 708.465156] USB Mass Storage support registered.
[ 708.477041] scsi4 : usb-storage 1-1.2:1.0
[ 708.477213] usbcore: registered new interface driver ums-realtek
[ 709.475917] scsi 4:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 709.477769] sd 4:0:0:0: Attached scsi generic sg2 type 0
[ 710.131709] sd 4:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 710.132653] sd 4:0:0:0: [sdb] Write Protect is off
[ 710.132660] sd 4:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 710.133694] sd 4:0:0:0: [sdb] No Caching mode page found
[ 710.133703] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[ 710.137908] sd 4:0:0:0: [sdb] No Caching mode page found
[ 710.137916] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[ 710.140549] sdb:
[ 710.143263] sd 4:0:0:0: [sdb] No Caching mode page found
[ 710.143273] sd 4:0:0:0: [sdb] Assuming drive cache: write through
[ 710.143282] sd 4:0:0:0: [sdb] Attached SCSI removable disk
[ 711.981919] ieee80211 phy0: START: tid 1 is not agg'able
[ 758.520811] ieee80211 phy0: START: tid 1 is not agg'able
[ 803.770458] ieee80211 phy0: START: tid 1 is not agg'able
[ 864.246875] usb 1-1.2: USB disconnect, device number 8
[ 868.352881] usb 1-1.2: new high-speed USB device number 9 using ehci_hcd
[ 869.076446] usb 1-1.2: device not accepting address 9, error -71
[ 869.093016] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 869.292653] usb 1-1.2: new high-speed USB device number 11 using ehci_hcd
[ 869.320734] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 869.520610] usb 1-1.2: new high-speed USB device number 12 using ehci_hcd
[ 869.711736] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 869.711741] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 869.711745] usb 1-1.2: Product: USB2.0-CRW
[ 869.711748] usb 1-1.2: Manufacturer: Generic
[ 869.711752] usb 1-1.2: SerialNumber: 20071114173400000
[ 869.727659] scsi5 : usb-storage 1-1.2:1.0
[ 870.298259] usb 1-1.2: USB disconnect, device number 12
[ 870.528192] usb 1-1.2: new high-speed USB device number 13 using ehci_hcd
[ 870.556400] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 870.852071] usb 1-1.2: new high-speed USB device number 14 using ehci_hcd
[ 870.955243] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 870.955255] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 870.955264] usb 1-1.2: Product: USB2.0-CRW
[ 870.955270] usb 1-1.2: Manufacturer: Generic
[ 870.955275] usb 1-1.2: SerialNumber: 20071114173400000
[ 870.972619] scsi6 : usb-storage 1-1.2:1.0
[ 871.321878] usb 1-1.2: USB disconnect, device number 14
[ 871.519682] usb 1-1.2: new high-speed USB device number 15 using ehci_hcd
[ 871.864317] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 871.864323] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 871.864327] usb 1-1.2: Product: USB2.0-CRW
[ 871.864331] usb 1-1.2: Manufacturer: Generic
[ 871.864334] usb 1-1.2: SerialNumber: 20071114173400000
[ 871.880379] scsi7 : usb-storage 1-1.2:1.0
[ 872.881868] scsi 7:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 872.883394] sd 7:0:0:0: Attached scsi generic sg2 type 0
[ 873.537359] sd 7:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 873.538175] sd 7:0:0:0: [sdb] Write Protect is off
[ 873.538182] sd 7:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 873.539099] sd 7:0:0:0: [sdb] No Caching mode page found
[ 873.539107] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 873.543066] sd 7:0:0:0: [sdb] No Caching mode page found
[ 873.543074] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 873.545698] sdb:
[ 873.548954] sd 7:0:0:0: [sdb] No Caching mode page found
[ 873.548964] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 873.548973] sd 7:0:0:0: [sdb] Attached SCSI removable disk
[ 874.904666] usb 1-1.2: USB disconnect, device number 15
[ 875.138300] usb 1-1.2: new high-speed USB device number 16 using ehci_hcd
[ 875.377589] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 875.377597] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 875.377602] usb 1-1.2: Product: USB2.0-CRW
[ 875.377606] usb 1-1.2: Manufacturer: Generic
[ 875.377611] usb 1-1.2: SerialNumber: 20071114173400000
[ 875.395620] scsi8 : usb-storage 1-1.2:1.0
[ 876.396676] scsi 8:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 876.398308] sd 8:0:0:0: Attached scsi generic sg2 type 0
[ 877.050200] sd 8:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 877.050941] sd 8:0:0:0: [sdb] Write Protect is off
[ 877.050944] sd 8:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 877.051688] sd 8:0:0:0: [sdb] No Caching mode page found
[ 877.051692] sd 8:0:0:0: [sdb] Assuming drive cache: write through
[ 877.055466] sd 8:0:0:0: [sdb] No Caching mode page found
[ 877.055474] sd 8:0:0:0: [sdb] Assuming drive cache: write through
[ 877.057980] sdb:
[ 877.060539] sd 8:0:0:0: [sdb] No Caching mode page found
[ 877.060543] sd 8:0:0:0: [sdb] Assuming drive cache: write through
[ 877.060547] sd 8:0:0:0: [sdb] Attached SCSI removable disk
[ 881.302111] usb 1-1.2: USB disconnect, device number 16
[ 881.503917] usb 1-1.2: new high-speed USB device number 17 using ehci_hcd
[ 881.532168] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 882.011722] usb 1-1.2: new high-speed USB device number 18 using ehci_hcd
[ 882.357797] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 882.357809] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 882.357818] usb 1-1.2: Product: USB2.0-CRW
[ 882.357825] usb 1-1.2: Manufacturer: Generic
[ 882.357833] usb 1-1.2: SerialNumber: 20071114173400000
[ 882.374033] scsi9 : usb-storage 1-1.2:1.0
[ 882.581646] usb 1-1.2: USB disconnect, device number 18
[ 882.811432] usb 1-1.2: new high-speed USB device number 19 using ehci_hcd
[ 882.914521] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 882.914531] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 882.914537] usb 1-1.2: Product: USB2.0-CRW
[ 882.914542] usb 1-1.2: Manufacturer: Generic
[ 882.914547] usb 1-1.2: SerialNumber: 20071114173400000
[ 882.930544] scsi10 : usb-storage 1-1.2:1.0
[ 883.929510] scsi 10:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 883.931691] sd 10:0:0:0: Attached scsi generic sg2 type 0
[ 884.587645] sd 10:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 884.588629] sd 10:0:0:0: [sdb] Write Protect is off
[ 884.588638] sd 10:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 884.589669] sd 10:0:0:0: [sdb] No Caching mode page found
[ 884.589676] sd 10:0:0:0: [sdb] Assuming drive cache: write through
[ 884.593775] sd 10:0:0:0: [sdb] No Caching mode page found
[ 884.593783] sd 10:0:0:0: [sdb] Assuming drive cache: write through
[ 884.596418] sdb:
[ 884.599118] sd 10:0:0:0: [sdb] No Caching mode page found
[ 884.599128] sd 10:0:0:0: [sdb] Assuming drive cache: write through
[ 884.599137] sd 10:0:0:0: [sdb] Attached SCSI removable disk
[ 903.309949] usb 1-1.2: USB disconnect, device number 19
[ 903.607560] usb 1-1.2: new high-speed USB device number 20 using ehci_hcd
[ 903.710767] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 903.710776] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 903.710782] usb 1-1.2: Product: USB2.0-CRW
[ 903.710787] usb 1-1.2: Manufacturer: Generic
[ 903.710792] usb 1-1.2: SerialNumber: 20071114173400000
[ 903.727273] scsi11 : usb-storage 1-1.2:1.0
[ 904.729854] scsi 11:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 904.731947] sd 11:0:0:0: Attached scsi generic sg2 type 0
[ 905.383762] sd 11:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 905.384680] sd 11:0:0:0: [sdb] Write Protect is off
[ 905.384689] sd 11:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 905.385534] sd 11:0:0:0: [sdb] No Caching mode page found
[ 905.385541] sd 11:0:0:0: [sdb] Assuming drive cache: write through
[ 905.389363] sd 11:0:0:0: [sdb] No Caching mode page found
[ 905.389370] sd 11:0:0:0: [sdb] Assuming drive cache: write through
[ 905.392128] sdb:
[ 905.395004] sd 11:0:0:0: [sdb] No Caching mode page found
[ 905.395013] sd 11:0:0:0: [sdb] Assuming drive cache: write through
[ 905.395022] sd 11:0:0:0: [sdb] Attached SCSI removable disk
[ 910.475095] usb 1-1.2: USB disconnect, device number 20
[ 910.676778] usb 1-1.2: new high-speed USB device number 21 using ehci_hcd
[ 910.780962] usb 1-1.2: device descriptor read/all, error -71
[ 910.797126] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 911.060764] usb 1-1.2: new high-speed USB device number 23 using ehci_hcd
[ 911.164100] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 911.164105] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 911.164109] usb 1-1.2: Product: USB2.0-CRW
[ 911.164112] usb 1-1.2: Manufacturer: Generic
[ 911.164115] usb 1-1.2: SerialNumber: 20071114173400000
[ 911.180142] scsi12 : usb-storage 1-1.2:1.0
[ 912.178906] scsi 12:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 912.180483] sd 12:0:0:0: Attached scsi generic sg2 type 0
[ 912.971100] sd 12:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 912.971950] sd 12:0:0:0: [sdb] Write Protect is off
[ 912.971958] sd 12:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 912.972797] sd 12:0:0:0: [sdb] No Caching mode page found
[ 912.972806] sd 12:0:0:0: [sdb] Assuming drive cache: write through
[ 912.976876] sd 12:0:0:0: [sdb] No Caching mode page found
[ 912.976883] sd 12:0:0:0: [sdb] Assuming drive cache: write through
[ 912.979529] sdb:
[ 912.982396] sd 12:0:0:0: [sdb] No Caching mode page found
[ 912.982404] sd 12:0:0:0: [sdb] Assuming drive cache: write through
[ 912.982410] sd 12:0:0:0: [sdb] Attached SCSI removable disk
[ 913.545862] usb 1-1.2: USB disconnect, device number 23
[ 913.603007] FAT-fs (sdb): Directory bread(block 480) failed
[ 913.603014] FAT-fs (sdb): Directory bread(block 481) failed
[ 913.603017] FAT-fs (sdb): Directory bread(block 482) failed
[ 913.603020] FAT-fs (sdb): Directory bread(block 483) failed
[ 913.603022] FAT-fs (sdb): Directory bread(block 484) failed
[ 913.603025] FAT-fs (sdb): Directory bread(block 485) failed
[ 913.603028] FAT-fs (sdb): Directory bread(block 486) failed
[ 913.603031] FAT-fs (sdb): Directory bread(block 487) failed
[ 913.603039] FAT-fs (sdb): Directory bread(block 488) failed
[ 913.603041] FAT-fs (sdb): Directory bread(block 489) failed
[ 913.751579] usb 1-1.2: new high-speed USB device number 24 using ehci_hcd
[ 913.854799] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 913.854809] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 913.854815] usb 1-1.2: Product: USB2.0-CRW
[ 913.854820] usb 1-1.2: Manufacturer: Generic
[ 913.854825] usb 1-1.2: SerialNumber: 20071114173400000
[ 913.870512] scsi13 : usb-storage 1-1.2:1.0
[ 914.870204] scsi 13:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 914.871962] sd 13:0:0:0: Attached scsi generic sg2 type 0
[ 915.527587] sd 13:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 915.528573] sd 13:0:0:0: [sdb] Write Protect is off
[ 915.528580] sd 13:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 915.529465] sd 13:0:0:0: [sdb] No Caching mode page found
[ 915.529472] sd 13:0:0:0: [sdb] Assuming drive cache: write through
[ 915.533706] sd 13:0:0:0: [sdb] No Caching mode page found
[ 915.533714] sd 13:0:0:0: [sdb] Assuming drive cache: write through
[ 915.536351] sdb:
[ 915.538993] sd 13:0:0:0: [sdb] No Caching mode page found
[ 915.539003] sd 13:0:0:0: [sdb] Assuming drive cache: write through
[ 915.539011] sd 13:0:0:0: [sdb] Attached SCSI removable disk
[ 917.128586] usb 1-1.2: USB disconnect, device number 24
[ 917.330211] usb 1-1.2: new high-speed USB device number 25 using ehci_hcd
[ 917.433880] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 917.433889] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 917.433895] usb 1-1.2: Product: USB2.0-CRW
[ 917.433901] usb 1-1.2: Manufacturer: Generic
[ 917.433905] usb 1-1.2: SerialNumber: 20071114173400000
[ 917.450314] scsi14 : usb-storage 1-1.2:1.0
[ 918.152346] usb 1-1.2: USB disconnect, device number 25
[ 918.413983] usb 1-1.2: new high-speed USB device number 26 using ehci_hcd
[ 918.517339] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 918.517348] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 918.517354] usb 1-1.2: Product: USB2.0-CRW
[ 918.517359] usb 1-1.2: Manufacturer: Generic
[ 918.517364] usb 1-1.2: SerialNumber: 20071114173400000
[ 918.533915] scsi15 : usb-storage 1-1.2:1.0
[ 919.536259] scsi 15:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 919.537814] sd 15:0:0:0: Attached scsi generic sg2 type 0
[ 920.189983] sd 15:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 920.190811] sd 15:0:0:0: [sdb] Write Protect is off
[ 920.190821] sd 15:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 920.191861] sd 15:0:0:0: [sdb] No Caching mode page found
[ 920.191868] sd 15:0:0:0: [sdb] Assuming drive cache: write through
[ 920.195942] sd 15:0:0:0: [sdb] No Caching mode page found
[ 920.195949] sd 15:0:0:0: [sdb] Assuming drive cache: write through
[ 920.198574] sdb:
[ 920.201426] sd 15:0:0:0: [sdb] No Caching mode page found
[ 920.201434] sd 15:0:0:0: [sdb] Assuming drive cache: write through
[ 920.201440] sd 15:0:0:0: [sdb] Attached SCSI removable disk
[ 932.994597] usb 1-1.2: USB disconnect, device number 26
[ 933.196287] usb 1-1.2: new high-speed USB device number 27 using ehci_hcd
[ 933.299609] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 933.299615] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 933.299619] usb 1-1.2: Product: USB2.0-CRW
[ 933.299622] usb 1-1.2: Manufacturer: Generic
[ 933.299625] usb 1-1.2: SerialNumber: 20071114173400000
[ 933.339045] scsi16 : usb-storage 1-1.2:1.0
[ 933.506400] usb 1-1.2: USB disconnect, device number 27
[ 933.704217] usb 1-1.2: new high-speed USB device number 28 using ehci_hcd
[ 933.732609] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 934.088091] usb 1-1.2: new high-speed USB device number 29 using ehci_hcd
[ 934.434187] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 934.434193] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 934.434197] usb 1-1.2: Product: USB2.0-CRW
[ 934.434200] usb 1-1.2: Manufacturer: Generic
[ 934.434204] usb 1-1.2: SerialNumber: 20071114173400000
[ 934.450163] scsi17 : usb-storage 1-1.2:1.0
[ 935.449929] scsi 17:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 935.450619] sd 17:0:0:0: Attached scsi generic sg2 type 0
[ 936.106902] sd 17:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 936.107769] sd 17:0:0:0: [sdb] Write Protect is off
[ 936.107772] sd 17:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 936.108514] sd 17:0:0:0: [sdb] No Caching mode page found
[ 936.108517] sd 17:0:0:0: [sdb] Assuming drive cache: write through
[ 936.111920] sd 17:0:0:0: [sdb] No Caching mode page found
[ 936.111927] sd 17:0:0:0: [sdb] Assuming drive cache: write through
[ 936.114566] sdb:
[ 936.120989] sd 17:0:0:0: [sdb] No Caching mode page found
[ 936.120995] sd 17:0:0:0: [sdb] Assuming drive cache: write through
[ 936.120998] sd 17:0:0:0: [sdb] Attached SCSI removable disk
[ 939.903949] usb 1-1.2: USB disconnect, device number 29
[ 940.357576] usb 1-1.2: new high-speed USB device number 30 using ehci_hcd
[ 940.548747] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 940.548753] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 940.548757] usb 1-1.2: Product: USB2.0-CRW
[ 940.548760] usb 1-1.2: Manufacturer: Generic
[ 940.548763] usb 1-1.2: SerialNumber: 20071114173400000
[ 940.564895] scsi18 : usb-storage 1-1.2:1.0
[ 941.563859] scsi 18:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 941.565702] sd 18:0:0:0: Attached scsi generic sg2 type 0
[ 942.221437] sd 18:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 942.222225] sd 18:0:0:0: [sdb] Write Protect is off
[ 942.222234] sd 18:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 942.223081] sd 18:0:0:0: [sdb] No Caching mode page found
[ 942.223090] sd 18:0:0:0: [sdb] Assuming drive cache: write through
[ 942.227301] sd 18:0:0:0: [sdb] No Caching mode page found
[ 942.227307] sd 18:0:0:0: [sdb] Assuming drive cache: write through
[ 942.229878] sdb:
[ 942.232467] sd 18:0:0:0: [sdb] No Caching mode page found
[ 942.232478] sd 18:0:0:0: [sdb] Assuming drive cache: write through
[ 942.232488] sd 18:0:0:0: [sdb] Attached SCSI removable disk
[ 946.465135] ieee80211 phy0: START: tid 1 is not agg'able
[ 949.372674] usb 1-1.2: USB disconnect, device number 30
[ 949.574100] usb 1-1.2: new high-speed USB device number 31 using ehci_hcd
[ 950.061699] usb 1-1.2: device not accepting address 31, error -71
[ 950.078446] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 950.277818] usb 1-1.2: new high-speed USB device number 33 using ehci_hcd
[ 950.306029] hub 1-1:1.0: unable to enumerate USB device on port 2
[ 950.593773] usb 1-1.2: new high-speed USB device number 34 using ehci_hcd
[ 950.939790] usb 1-1.2: New USB device found, idVendor=0bda, idProduct=0159
[ 950.939794] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 950.939797] usb 1-1.2: Product: USB2.0-CRW
[ 950.939799] usb 1-1.2: Manufacturer: Generic
[ 950.939801] usb 1-1.2: SerialNumber: 20071114173400000
[ 950.955354] scsi19 : usb-storage 1-1.2:1.0
[ 951.955469] scsi 19:0:0:0: Direct-Access Generic- Multi-Card 1.00 PQ: 0 ANSI: 0 CCS
[ 951.957130] sd 19:0:0:0: Attached scsi generic sg2 type 0
[ 952.612802] sd 19:0:0:0: [sdb] 3862528 512-byte logical blocks: (1.97 GB/1.84 GiB)
[ 952.613507] sd 19:0:0:0: [sdb] Write Protect is off
[ 952.613511] sd 19:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 952.614258] sd 19:0:0:0: [sdb] No Caching mode page found
[ 952.614262] sd 19:0:0:0: [sdb] Assuming drive cache: write through
[ 952.619391] sd 19:0:0:0: [sdb] No Caching mode page found
[ 952.619397] sd 19:0:0:0: [sdb] Assuming drive cache: write through
[ 952.621895] sdb:
[ 952.625756] sd 19:0:0:0: [sdb] No Caching mode page found
[ 952.625761] sd 19:0:0:0: [sdb] Assuming drive cache: write through
[ 952.625765] sd 19:0:0:0: [sdb] Attached SCSI removable disk
有什么帮助吗？
有时当它看不到时，它会在 dmesg 中写入这样的错误：
[ 1373.209390] usb 1-1.2: new high-speed USB device number 37 using ehci_hcd
[ 1373.860861] usb 1-1.2: device not accepting address 37, error -71
[ 1373.877631] hub 1-1:1.0: unable to enumerate USB device on port 2
答案1
我现在使用的是 ubuntu 14.04。我没有收到错误消息，但每次插入 SD（HC）卡时，它都无法安装。我不认为这是硬件问题，因为同样的设备在 ubuntu 13.10 上也能正常工作，这得益于以下几点：
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/925760/comments/75
这有帮助吗？