On 03/18/13 23:39, Ronald F. Guilmette wrote:
1)  What is the best way to debug this?  I have seen HPS suggest to others
with USB problems that they either (a) use the usbdump(8) command to get
more info about the problems or else (b) compile and install a new kernel
in which the option USB_DEBUG has been defined.  Which should I do, and
how may I interpret the results in either case?

I see two kind of hangs:

1) IRQ is spinning
2) DMA is going wild in the memory

In sys/dev/usb/controller/xhci.c there are debug prints, DPRINTF() and DPRINTFN(). You probably want to have a print in the interrupt routine. Just search for "interrupt". Debug level is controlled via sysctl hw.usb.xhci.debug=X

2)  What are the command timeouts set to in the XHCI driver and how can I
     increase them?  (Perhaps my card is just barely meeting the published
     USB standard timing specs, and just need a tiny bit more time?)

The XHCI is an active USB controller. That means many high-level USB commands must be fed into it using separate commands. These have nothing to do with what is transferred to the USB device.

3)  What exactly is "hw.usb.no_cs_fail" ?

This just instructs the system to not re-enumerate the device on repeated clear stall failures.

4)  What exactly is "hw.usb.u3g.debug" ?

That's debugging for u3g driver module.

5)  What exactly is "diveration" ?

Where did you find this?

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