On Sat, 29 Sep 2012, Lassi Väätämöinen wrote:

> On Friday, September 28, 2012 05:16 PM, Alan Stern wrote:
> > On Fri, 28 Sep 2012, [iso-8859-1] Lassi V��t�m�inen wrote:
> >
> >> Ok. How can I tell when this error is visible in the logs? Status field is 
> >> -22?
> 
> >
> > If that is the error you are most worried about, then yes.  There were
> > other errors (URBs still pending) that caused khubd to hang, but there
> > was no way to tell why they occurred.
> 
> I am really not sure which error I should be worried about, if not that 
> -22 ?

You should concentrate on whichever error occurs first.  Everything
else could easily be a side-effect of the first error.

> The new usbmon log with kernel 3.6-rc7 is available here, with the dmesg 
> log as well (the dmesg log does not show much to me...):
> https://bugs.launchpad.net/ubuntustudio/+bug/1035602/comments/3
> https://bugs.launchpad.net/ubuntustudio/+bug/1035602/comments/4

I'll look through them later...

> >> Would it be better to take the usbmon trace from all buses (0u, right?).
> >
> > I don't know; it depends on what the test is doing.  Which USB devices
> > does it read from and which devices does it write to?  Are there any
> > other unrelated USB devices attached (hint: it helps if there aren't).
> >
> 
> My test case: I have an MAudio MobilePre USB soundcard plugged in, Jackd 
> is running, and I am playing back a track in Ardour.

Where is the track stored?  On a USB disk?  Or is the MobilePre sound
card the only USB device involved in this test?  If it is then you
shouldn't have any other USB devices plugged into the computer while
the test is running, which would mean that it doesn't make any
difference whether you capture 0u or the file for the sound card's bus.

> >> Or which usbmon socket should I take the traces on?
> >
> > The ones that get the errors you want to investigate.  Unforunately the
> > error messages printed out by the snd-usb-audio driver aren't very
> > helpful; they don't say what device they relate to.
> 
> Okay, this is sort of a given. I was merely asking that is it of any use 
> to listen to all buses, or is it just to a single one; the one that 
> causes the errors.

If the events on the other buses are not relevant to the test then 
there's no point listening to them.

Alan Stern

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