On Fri, Dec 28, 2012 at 10:45 PM, Grant <emailgr...@gmail.com> wrote: > I'm trying to get a USB sound card to behave in a certain way which > requires it to think the computer has gone to sleep. I'm told the > specific signal the sound card looks for is if the USB controller has > been physically powered down. Should I unload a kernel module to > accomplish this, or do I need to actually put the computer into sleep > mode?
I don't think you can turn USB port off, at best you can suspend it, which is not truly 100% powered-down. I think you might be able to power off an entire hub (and never power it back on again until reboot) but I'm not sure if that will be any better than just unplugging the cable. You might be able to build some kind of simple USB on/off switch. :) Check out /sys/bus/usb/devices/[yourdevice]/power/level for current status and you can echo different commands to that same file to attempt to change its status. Check out the power management settings and documentation in the linux kernel for your options.
