Intel Extensible Firmware Interface - Manual (Page 572)

Extensible Firmware Interface Specification
14-32 12/01/02 Version 1.10
EFI_USB_HC_PROTOCOL.ClearRootHubPortFeature()
Summary
Clears a feature for the specified root hub port.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_USB_HC_PROTOCOL_CLEAR_ROOTHUB_PORT_FEATURE) (
IN EFI_USB_HC_PROTOCOL
*This
IN UINT8 PortNumber,
IN EFI_USB_PORT_FEATURE PortFeature
);
Parameters
This A pointer to the EFI_USB_HC_PROTOCOL instance. Type
EFI_USB_HC_PROTOCOL is defined in Section 14.1.
PortNumber Specifies the root hub port whose feature is requested to be
cleared. This value is zero-based. For example, if a root hub has
two ports, then the first port is number 0, and the second port is
numbered 1.
PortFeature Indicates the feature selector associated with the feature clear
request. The port feature indicator (
EFI_USB_PORT_FEATURE )
is defined in the “Related Definitions” section of the
SetRootHubPortFeature() function description and in
Table 14-3.
Description
This function clears the feature specified by PortFeature for the USB root hub port specified
by PortNumber . Clearing a feature disables that feature or stops a process associated with that
feature. For the meanings about the defined features, 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 ,
EfiUsbPortPower , EfiUsbPortConnectChange , EfiUsbPortResetChange ,
EfiUsbPortEnableChange , EfiUsbPortSuspendChange , or
EfiUsbPortOverCurrentChange , then EFI_INVALID_PARAMETER is returned.