Issue
On a Raspberry PI 3B+, it's simple to turn power on its four USB ports off and on. Simply write a "0" to /sys/devices/platform/soc/3f980000.usb/buspower to turn power off and a "1" to turn power on.
The same method doesn't work on Raspberry PI 4B, 4GB (the hex number before ".usb" is different, that's NOT the problem). I have tried uhubctl and hub-ctl as well without any success. I have used a USB power meter to measure the voltage on the ports. It doesn't change. Un a PI 3B+ it changes as expected.
Does the PI 4 support turning USB power off and on in software at all? If it does, how to do it? Or is there a bug somewhere that has to be fixed to make it work? I use the newest Rapbian on both the Pi 3B+ and the Pi 4.
Solution
Yes, uhubctl supports RPi4B, I have recently added support for it - you need to use uhubctl version 2.4.0 or later (or build it from master branch). It is also necessary to update USB firmware using sudo rpi-eeprom-update to make power switching actually work.
Note that you are missing out by using sysfs method to turn USB off on RPi3B+ - using uhubctl you can control either all 4 ports, or 2 of them independently. RPi4B only supports turning off all ports at once.
Answered By - mvp
