Cut a projector’s wake time from ten seconds to under one

one thing that was bothering me is the wake up time. turns out it was two linux computers inside, an android tv box, and a separate board that drives the laser and optics, that were talking to each other over usb and gpio.

when it sleeps, it cuts the 5v to the laser computer, resulting in a cold boot on wake up while another computer polls it in 1s intervals. android is awake in 0.4s, but the controller it killed takes another 10s.

i found a way to keep it powered without root, so i can send it to sleep with power to both boards. i found a userspace function called vmute that does exactly what i need. it cuts the laser instantly, and comes back in under 1s.