# [USB] Activate / deactivate a single port (open)

## pcmaster

Hello,

Certain hardware USB devices are not detected (sometimes) if the device was plugged to the computer before the computer is powered on. If you power off the PC with the device connected, when you power on again the pc, the device, sometimes is recognized and sometimes not. If not recognized, an lsusb don't shows device ids.

If you boot up with Windows, the problem is still present, then this is a hardware issue.

I think that if i can de-activate a single USB port, to simulate a device-unplug, and then re-activate the USB port, in order to simulate USB reconnect, is possible that the device can be re-activated.

If possible to do it?

Thanks, and sorry for the bad english.

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## JeliJami

i'm not sure you can do this with a single USB port, but if you have usb support built as a kernel module, you could do something like this (if the USB device is a storage device):

```
# rmmod usb-storage; modprobe usb-storage
```

this would re-initialise the usb-storage support, and 'revive' your device

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## pcmaster

Is'n a usb-storage device, is a dvb USB 2.0 adapter.

if y connect it to the PCI USB 2.0 adapter, no problem with the device detection, but the pci card don't support high power devices and fails ramdomly.

If i connect the device to the motherboard USB 2.0 ports, the device has the correct power, but sometimes is not detected in the USB bus if the system is powered on with the device adapter. Is a hardware issue, not a software issue. You can reboot after reboot and the device is never detected, in both Linux and Windows. Unplugging the device from the USB bus, and re-plugging it, or powering the system with the device unplugged, and plug-in it with the system powered on, then the device is always detected.

Of course, when the device is not detected is don't displayed by an lsusb or in usbview.

If i find a method to "shut down" a USB port, disconnecting any power out in this connector, i can, wait a few seconds, and then reactivate the port, in order to do a "unplug and re-plug emulation" the device may be probably (i'm not sure) detected.

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