Thursday, December 2, 2010

USB gives a lesson in physics

With a recently bought mouse:

[176149.256699] hub 3-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
[176149.256706] hub 3-0:1.0: over-current change on port 1
[176149.357643] usb 3-1: USB disconnect, address 3
[176149.569692] usb 3-1: new low speed USB device using uhci_hcd and address 4
[176149.734362] usb 3-1: New USB device found, idVendor=093a, idProduct=2510
[176149.734371] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[176149.734377] usb 3-1: Product: USB OPTICAL MOUSE

Googling shows affected are many, yet few good explanations are provided. This good post explains that it is indeed caused by an electrostatic discharge (ESD), which, kernel can be agreed with, may be seen as an extreme case of electo-magnetic interference (EMI).

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