Controlling a USB power supply (on/off) with Linux

by

According to the docs, there were several changes to the USB power management from kernels 2.6.32, which seem to settle in 2.6.38. Now you’ll need to wait for the device to become idle, which is governed by the particular device driver. The driver needs to support it, otherwise the device will never reach this state. Unluckily, now the user has no chance to force this. However, if you’re lucky and your device can become idle, then to turn this off you need to:

echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend"
echo "auto" > "/sys/bus/usb/devices/usbX/power/level"

or, for kernels around 2.6.38 and above:

echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend_delay_ms"
echo "auto" > "/sys/bus/usb/devices/usbX/power/control"

This literally means, go suspend at the moment the device becomes idle.

So unless your fan is something “intelligent” that can be seen as a device and controlled by a driver, you probably won’t have much luck on current kernels.

More Related Contents:

  1. 32-bit absolute addresses no longer allowed in x86-64 Linux?
  2. How to convert DOS/Windows newline (CRLF) to Unix newline (LF) in a Bash script
  3. How do I send a file as an email attachment using Linux command line?
  4. What’s the best way to send a signal to all members of a process group?
  5. How to prevent a background process from being stopped after closing SSH client in Linux
  6. What is double dot(..) and single dot(.) in Linux?
  7. What does the number in parentheses shown after Unix command names in manpages mean?
  8. How to install latest version of git on CentOS 8.x/7.x/6.x
  9. Docker can’t connect to docker daemon
  10. Adding a new entry to the PATH variable in ZSH
  11. How can I delete a newline if it is the last character in a file?
  12. Quickly create a large file on a Linux system
  13. Redirect STDERR / STDOUT of a process AFTER it’s been started, using command line?
  14. Makefiles with source files in different directories
  15. Use of floating point in the Linux kernel
  16. Error when using Git credential helper with gnome-keyring as Sudo
  17. How do I change permissions for a folder and its subfolders/files?
  18. How can I generate a list of files with their absolute path in Linux?
  19. Using the passwd command from within a shell script
  20. Command to get time in milliseconds
  21. In Linux, how to tell how much memory processes are using?
  22. How does Linux determine the next PID?
  23. How does vi restore terminal content after quitting it?
  24. Monitor Directory for Changes
  25. Trying to understand gcc’s complicated stack-alignment at the top of main that copies the return address
  26. How to kill zombie process
  27. How do I script a “yes” response for installing programs?
  28. Print date for the monday of the current week (in bash)
  29. How can I trim white space from a variable in awk?
  30. ARM inline asm: exit system call with value read from memory

Leave a Comment