On Thu, Mar 06, 2025 at 09:06:23PM +0000, Colin Evans wrote:
Please try collecting a usbmon trace for bus 2 showing the problem. Ideally the trace should show what happens from system boot-up, but there's no way to do that. Instead, you can do this (the first command below disables the bus, the second starts the usbmon trace, and the third re-enables the bus):
echo 0 >/sys/bus/usb/devices/usb2/bConfigurationValue cat /sys/kernel/debug/usb/usbmon/2u >usbmon.txt & echo 1 >/sys/bus/usb/devices/usb2/bConfigurationValue
Then after enough time has passed for the errors to show up, kill the "cat" process and post the resulting trace file. (Note: If your keyboard is attached to bus 2, you won't be able to use it to issue the second and third commands. You could use a network login, or put the commands into a shell file and run them that way.)
In fact, you should do this twice: The second time, run it on machine 2 with the powered hub plugged in to suppress the errors.
Alan Stern
Happy to try this, but as it stands there is no such file, or file-like thing, on my machine-
# ls /sys/kernel/debug/usb/usbmon/2u ls: cannot access '/sys/kernel/debug/usb/usbmon/2u': No such file or directory
# find /sys/kernel/debug/usb -name "2u" #
# ls /sys/kernel/debug/usb devices ehci ohci uhci uvcvideo xhci
It seems something is missing?
Ah -- you have to load the usbmon module first:
modprobe usbmon
Some distributions do this for you automatically.
Alan Stern