pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32 什么原因呢？

[679820.597511] usb 1-2.1: new full-speed USB device number 31 using xhci_hcd
[679820.698259] usb 1-2.1: New USB device found, idVendor=067b, idProduct=2303
[679820.698278] usb 1-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[679820.698281] usb 1-2.1: Product: USB-Serial Controller
[679820.698283] usb 1-2.1: Manufacturer: Prolific Technology Inc.
[679820.698753] pl2303 1-2.1:1.0: pl2303 converter detected
[679820.699978] usb 1-2.1: pl2303 converter now attached to ttyUSB0
[680156.090246] pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32
[680169.725237] pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32

用 usb hub 连接串口，通信过程中一段时间后就会这样。 U 盘拷贝数据也会出现问题。
这是系统问题还是硬件问题？
原以为是垃圾的 orico hub 的问题导致的，后换了一个 amazon basics ，也这样，都是 VIA usb3.0 的芯片。

Linux WORKU 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 15:35:06 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux