Thought I'd share this in case others are encountering something like it...
I have a new-ish Dell XPS 8700 machine running Ubuntu 13.10 that, when
hooked up to Firefox OS devices via USB would find the devices
constantly disconnecting and reconnecting. As in, at a rate of anywhere
from several times a second to once every few seconds I'd see "USB
disconnect, device number N" followed 0.2 seconds later by "new
high-speed USB device number N+1 using xhci_hcd", only to find a
disconnect notice for that 0.3 seconds later. This made it rather hard
to use "adb logcat" or remote debugging tools or push new versions of an
app.
Long story short, the problem exhibited when using the USB 2.0 ports on
top of the machine, but the USB 3.0 ports at the front of the machine
are fine (or at least much better). I don't understand what's happening
in any useful fashion.
Additional notes:
- This happened with various different USB 2.0 cables.
- Blacklisting things like qmi_wwan/cdc_wdm and usb_storage had no
effect other than to reduce the amount of syslog spam. Same with
removing the libmtp udev rules at /lib/udev/rules.d/69-libmtp.rules
(there was a note about mtp-probe in the log too).
- I definitely was just observing this with a trunk-ish Hamachi
- Just reproduced on my trunk-ish Nexus 4 sometimes after 15-20
seconds. However, the nexus 4 on the USB 3.0 port will sometimes drop
any existing "adb logcat" as something like the following shows up in
the syslog: "usb 3-11: reset high-speed USB device number 59 using
xhci_hcd" followed by 5 lines that look like "xhci_hcd 0000:00:14.0:
xHCI xhci_drop_endpoint called with disabled ep ffff8807c328d700"
- I think the nexus 4 might have been fine in fastboot mode
- I think my GP Keon running 1.2 did something similar, but it's
currently lost somewhere
- All devices were configured to enable remote debugging and with their
lock screens disabled
- The system was running with A04 BIOS, I upgraded to A06 but there was
no change and no options in either version to do things like disable
XHCI mode, etc.
- uname -rvm: 3.11.0-15-generic #25-Ubuntu SMP Thu Jan 30 17:22:01 UTC
2014 x86_64
- I wanted to try forcing the system to use ehci-hcd instead of
xhci-hcd, but the Ubuntu kernel builds both drivers in so I think the
modprobe.d "blacklist xhci-hcd" option was not going to work, but I
could be confused.
Andrew
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