Possible causes of EOVERFLOW (babble) error?

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Dear Experts,

What can anyone tell me about the EOVERFLOW error (-75), reported e.g. 
as follows:

Oct 23 14:45:15 egypt kernel: usb 3-2.1: device descriptor read/all, 
error -75

I understand that it means "babble", i.e. that the device was still 
transmitting when the end-of-frame was due.  I'm seeing this reported 
by Linux when I plug in my home-brew USB device, and transmitting (for 
example) 65536 bytes instead of 0 bytes is exactly the sort of mistake 
that I could have made.  But... neither the USB analyser that I have 
borrowed nor my scope can see any evidence of such activity on the 
bus.  So I'm wondering if perhaps that error code is overloaded with 
some other meaning.

My device is full-speed, and I see the same behaviour when it's 
connected directly to the PC (uhci) and when it's connected via a 
high-speed hub (ehci).

Any ideas anyone?  (And if there is anyone else with a CATC analyser, 
have you seen any evidence that its babble-error-detection feature 
actually works?)



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