Ubuntu – Power on/off USB ports

power-managementusb

Is it possible to on/off a specific USB port using the terminal in Ubuntu?

lsusb displays the following result:

Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 2232:1020
Bus 002 Device 009: ID 0bc2:a013 Seagate RSS LLC
Bus 002 Device 003: ID 0a5c:219c Broadcom Corp.

Seagate is my external hard disk drive. Can I power it off in the terminal?

I tried Controlling a USB power supply (on/off) with Linux. But I am confused about what should be replaced in place of usbX.

Best Answer

All of the previous answers talk about a USB suspend mechanism, i.e. a "logical power-off", they will never physically cut the VBUS +5V from the USB port.

Only a few hubs can actually cut VBUS as described here.

The hubpower tool can do it (if the hub supports it).

Related Solutions

Ubuntu – Set webcam on different USB bus

The answer is: it's not actually your problem.

Some logitech cameras have usb bandwidth allocation bug. Lets see if that's the case.

cat /sys/kernel/debug/usb/devices | grep "B: "

will give you current bandwidth allocation of all usb hubs, output will be something like this:

B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
B:  Alloc= 35/900 us ( 4%), #Int=  3, #Iso=  0
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0

As you can see, I currently have 35 mbps allocated of my usb3 hub. The problem with some logitech cameras, though, is that they will always allocate as much as they can get (480 mbps), disregarding of mode. And so it's down to simple arithmetic as 480 + 480 > 900 and second camera just "won't fit".

As long as your cameras are plugged in the same hardware usb hub, you will have that problem.

Also bear in mind, that webcamera usually allocates 128mbps in MJPEG and 424mbps in uncompressed mode for 640x480.

Best Answer

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Ubuntu – Set webcam on different USB bus

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