On 01/09/2023 18:08, Tom Browder wrote:
When switching the KVM between the Win and Deb hosts, I could see the
mouse was not getting power (no sensor light) nor was the keyboard or
monitor screen. So that is probably why I could not wake up the Debian
PC by stirring the mouse or hitting a key.
My conclusion: I need to find out which sleep modes turn off power to
the external input devices.
It might depend on USB hubs on motherboards (wiring and whether
particular chips retain power and support switching off power on
particular ports) and on wake on USB implementation and settings in
firmware.
An example: an external keyboard is connected through a USB hub built-in
into a monitor. The laptop may be waked up by pressing any key on the
external keyboard. However if monitor is powered off (using its power
button or the switch on a AC power line filter) then wake on USB does
not work any more after the monitor switched on again.
Once I tried if I can power off laptop USB ports to avoid battery drain
in sleep state by an external USB hub. I was unable to do it for a
particular laptop. The uhubctl project has some list of supported hardware.
