On Sun, Jun 27, 2021 at 09:24:45PM -0400, Matt Corallo wrote:

On 6/27/21 21:16, Alan Stern wrote:

quoted

You mean that only devices in the first group are affected by this bug?
Devices in the second group are always detected correctly regardless of
what else is plugged in?  (This contradicts what you wrote above.)

Correct. Ignoring hotplug (ie on fresh boot or lsusb -vvv), the devices in
the second group work great. The devices in the first group do too, but only
if a device from the second group is present.

Okay.  You can try collecting some usbmon traces to see what's going on.  

First test: Boot with nothing plugged in, start a usbmon trace for bus 0 
(cat /sys/kernel/debug/usb/usbmon/0u >mon1.txt), plug in a first-group 
device, run lsusb -v to trigger enumeration, and then kill the "cat" 
process.

Second test: Same as the first except that you boot with a second-group 
device already plugged in.

The differences between the two traces may indicate where the problem 
is.

Alan Stern