Power OFF and ON USB device in linux (ubuntu)
http://loginroot.com/power-off-and-on-usb-device-in-linux-ubuntu/
There are two methods of doing this. So first method is for kernels after 2.6.32, and second for older ones.
To view kernel version, simply enter:
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> uname -r
3.8.0-29-generic
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find Your USB device, no mather what it is USB flash drive, Yubikey, USB disk drive:
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> lsusb
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0024 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 002 Device 005: ID 12d1:14db Huawei Technologies Co., Ltd.
Bus 002 Device 006: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
> lsusb -t
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
|__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M
|__ Port 1: Dev 5, If 0, Class=comm., Driver=cdc_ether, 480M
|__ Port 1: Dev 5, If 1, Class=data, Driver=cdc_ether, 480M
|__ Port 5: Dev 6, If 0, Class=hub, Driver=hub/4p, 480M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
|__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/6p, 480M
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Our target is:
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Bus 002 Device 005: ID 12d1:14db Huawei Technologies Co., Ltd.
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Which is located at 2-1.1 (tree part where device 5 is located)
First method (newer kernel)
To turn it off simply echo address:
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echo '2-1.1' > /sys/bus/usb/drivers/usb/unbind
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here is result from syslog:
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Feb 20 12:03:27 vgsms6 kernel: [ 1734.993667] cdc_ether 2-1.1:1.0 eth2: unregister 'cdc_ether' usb-0000:00:1d.0-1.1, CDC Ethernet Device
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Unfortunately this device was still visible in lsusb, so I turned off whole usb hub there (2-1), and voila, usb device gone.
To enable it, echo same address to “bind” part, for example:
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echo '2-1.1' > /sys/bus/usb/drivers/usb/bind
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Second method (older kernel)
You need to go to devices:
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cd /sys/bus/usb/devices
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Addressess will be listed similar:
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/sys/bus/usb/devices# ls -alh
total 0
drwxr-xr-x 2 root root 0 Feb 20 11:34 .
drwxr-xr-x 4 root root 0 Feb 20 11:34 ..
lrwxrwxrwx 1 root root 0 Feb 20 11:34 1-0:1.0 -> ../../../devices/pci0000:00/0000:00:1a.0/usb1/1-0:1.0
lrwxrwxrwx 1 root root 0 Feb 20 11:34 1-1 -> ../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1
lrwxrwxrwx 1 root root 0 Feb 20 11:34 1-1:1.0 -> ../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1:1.0
lrwxrwxrwx 1 root root 0 Feb 20 11:34 2-0:1.0 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-0:1.0
lrwxrwxrwx 1 root root 0 Feb 20 11:34 2-1 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1.1 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.1
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1:1.0 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1:1.0
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1.1:1.0 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.1/2-1.1:1.0
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1.1:1.1 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.1/2-1.1:1.1
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1.5 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5
lrwxrwxrwx 1 root root 0 Feb 20 12:34 2-1.5:1.0 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5:1.0
lrwxrwxrwx 1 root root 0 Feb 20 11:34 usb1 -> ../../../devices/pci0000:00/0000:00:1a.0/usb1
lrwxrwxrwx 1 root root 0 Feb 20 11:34 usb2 -> ../../../devices/pci0000:00/0000:00:1d.0/usb2
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So go to in our example 2-1.1/power (full path /sys/bus/usb/devices2-1.1/power)
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cd /sys/bus/usb/devices2-1.1/power
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to turn off device:
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echo suspend > level
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to turn on:
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echo on > level
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~ $ sudo echo ‘1-1.2’ > /sys/bus/usb/drivers/usb/unbind
-bash: /sys/bus/usb/drivers/usb/unbind: Permission denied
Thanks, finally got it working! :)
Anonymous: your command executes “echo ‘1-1.2′” under sudo, and then tries to write that to /sys/bus/usb/drivers/usb/unbind as the normal user again. Try this: echo ‘1-1.2″ | sudo tee /sys/bus/usb/drivers/usb/unbind
You could also use a switchable USB hub.
Something like this https://www.yepkit.com/products/ykush
but it’s more expensive :)
Smart way of leaving a backlink.
I encourage doing opensource projects :)
Usually the budget depends on what are the requirements. For a simple “faulty” usb emergency device reset I would use my way (I wouldn’t expect something to break, would I?).
But for day to day planned switch off/on I’d consider such device.
Thanks for sharing Your product.
That’s pretty useful thing, it should have more reliable switching capability and it’s more powerful than a server usb port.
You should consider making a bigger hub, as it seems to be possible to use it as a powersource for usb devices (2Amps of current).
For example external usb 2.5 hdd would already take 2 ports, leaving only one free.
Or make an usb controlled power source switcher with relays, it would perfectly go as a combo with this usb hub device :)
Fully agree with you, the best approach depends of the requirements.
Those are cool ideas for improving the product.
Cheers
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