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Re: kern/51524: USB vs. serial problems
The following reply was made to PR kern/51524; it has been noted by GNATS.
From: David Holland <dholland-bugs%netbsd.org@localhost>
Subject: Re: kern/51524: USB vs. serial problems
Date: Mon, 3 Oct 2016 00:38:51 +0000
On Sun, Oct 02, 2016 at 10:15:00PM +0000, John D. Baker wrote:
> > 4 hours later I saw the following in the kernel log:
> >ehci_sync_hc: cv_timedwait() = 35
> Curious. This exact same error has been observed with USB network
> devices [...]
I just changed it so it will print
ehci_sync_hc: timed out
which is no more helpful but less mysterious.
It seems that ehci_sync_hc pokes the ehci and tells it to send an
interrupt when it's done (with something-or-other) and then waits; the
print means that the interrupt didn't happen after one second.
I notice though that ehci_device_intr_abort() says this:
* XXX - abort_xfer uses ehci_sync_hc, which syncs via the advance
* async doorbell. That's dependent on the async list, wheras
* intr xfers are periodic, should not use this?
and I wonder if that's part of the problem...
David A. Holland
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