Driver for Enhanced Host Controller Interface (EHCI) USB controllers

You must be root to start this driver.


io-usb -d ehci [option[,option...]] &


ARM and x86


int_thresh= num
Interrupt microframe threshold. Valid values are 1,2,4,8,16,32,64. The default value is 8, which is a 1ms interrupt rate. The chip will interrupt after a 1ms period (USB frame) if there are completed transactions. Setting the value to 1 lets the chip interrupt after 125us (USB microframe) if there are completed transactions.
ioport= addr
Register the base address. The default is to scan the PCI bus.
irq= num
The interrupt request number.
memory= name
Use the specified typed memory for DMA descriptors (endpoint descriptor, transfer descriptors, and so on).
Don't disable system management. The default is to disable it.
num_ed= num
The number of endpoint descriptors to preallocate.
num_td= num
The number of transfer descriptors to preallocate.
pindex= num
Instance of controller on PCI bus to apply argument.
ports= port : port...
Set the enumeration order of each root port. Use colons to separate the port numbers.
verbose= num
Set verbosity level.


The server provides support for computers that have Enhanced Host Controller Interface (EHCI) USB controllers. This server creates the /dev/io-usb/ device.


Scan PCI bus for all available controllers.

io-usb -dehci

If you specify arguments you'll need to include pindex arguments for all controllers you wish to use. The value for the pindex argument should start from 0. Attach to the 1st and 3rd controller instance and set the verbose argument on the 1st, as follows:

io-usb -dehci pindex=0,verbose=4,pindex=2 &

Last modified: 2013-12-21

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