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
