usb_control_msg() in return: -22

[gjf]

Hi all!
Asus RT-AC68U, latest Merlin release.

Has anyone an idea what does it mean:

Jan 22 13:57:52 syslog: usb_control_msg() in return: -22

in syslog?

This message floods it occasionally.

I am using USB stick as swap connected via USB Hub on USB 2.0 port. The same hub is used for connection Epson Stylus Photo TX650 - and the printer is equipped with USB port. Spin down function is disabled for all devices connected via USB hub.