Intel Extensible Firmware Interface - Manual (Page 571)

Protocols — USB Support
Version 1.10 12/01/02 14-31
The feature values specified in the enumeration variable have special meaning. Each value
indicates its bit index in the port status and status change bitmaps, if combines these two bitmaps
into a 32-bit bitmap. The meaning of each port feature is listed in Table 14-3.
Table 14-3. USB Port Feature
Port Feature For
SetRootHubPortFeature
For ClearRootHubPortFeature
EfiUsbPortEnable Enable the given port of the
root hub. Disable the given port of the root hub.
EfiUsbPortSuspend Put the given port into
suspend state. Restore the given port from the previous
suspend state.
EfiUsbPortReset Reset the given port of the
root hub. Clear the RESET signal for the given
port of the root hub.
EfiUsbPortPower Power the given port. Shutdown the power from the given port.
EfiUsbPortConnectChange N/A. Clear
USB_PORT_STAT_C_CONNECTION
bit of the given port of the root hub.
EfiUsbPortEnableChange N/A. Clear USB_PORT_STAT_C_ENABLE bit
of the given port of the root hub.
EfiUsbPortSuspendChange N/A. Clear USB_PORT_STAT_C_SUSPEND
bit of the given port of the root hub.
EfiUsbPortOverCurrentChange N/A. Clear
USB_PORT_STAT_C_OVERCURRENT
bit of the given port of the root hub.
EfiUsbPortResetChange N/A. Clear USB_PORT_STAT_C_RESET bit
of the given port of the root hub.
Description
This function sets the feature specified by PortFeature for the USB root hub port specified by
PortNumber . Setting a feature enables that feature or starts a process associated with that
feature. For the meanings about the defined features, please refer to Table 14-1 and Table 14-2.
The number of root hub ports attached to the USB host controller can be determined with the
function
GetRootHubPortNumber() . If PortNumber is greater than or equal to the number
of ports returned by GetRootHubPortNumber() , then EFI_INVALID_PARAMETER is
returned. If PortFeature is not EfiUsbPortEnable , EfiUsbPortSuspend ,
EfiUsbPortReset nor EfiUsbPortPower , then EFI_INVALID_PARAMETER is returned.
Status Codes Returned
EFI_SUCCESS The feature specified by PortFeature was set for the USB
root hub port specified by PortNumber .
EFI_INVALID_PARAMETER PortNumber is invalid or PortFeature is invalid for this
function.