set usb2642 hubs' ports' pm_qos_no_power_off to 0
the following lets our usb hubs' ports power off. It doesn't make anything worse but could save power (not verified).
#!/bin/bash
# let the usb2642 hubs' port power off:
# sd cardreader
echo 0 | sudo tee /sys/bus/usb/devices/1-1/1-1:1.0/1-1-port1/power/pm_qos_no_power_off
# modem
echo 0 | sudo tee /sys/bus/usb/devices/1-1/1-1:1.0/1-1-port2/power/pm_qos_no_power_off
# nothing connected
echo 0 | sudo tee /sys/bus/usb/devices/1-1/1-1:1.0/1-1-port3/power/pm_qos_no_power_off
Is it possible to set this via udev? I couldn't find it via udevadm info -a
...
For details see https://www.kernel.org/doc/html/v5.17/driver-api/usb/power-management.html (" This writable flag controls the state of an idle port. Once all children and descendants have suspended the port may suspend/poweroff provided that pm_qos_no_power_off is ‘0’. If pm_qos_no_power_off is ‘1’ the port will remain active/powered regardless of the stats of descendants. Defaults to 1. ")