Intel Extensible Firmware Interface - Manual (Page 590)

Extensible Firmware Interface Specification
14-50 12/01/02 Version 1.10
EFI_USB_IO_PROTOCOL.UsbIsochronousTransfer()
Summary
This function is used to manage a USB device with an isochronous transfer pipe. An Isochronous
transfer is typically used to transfer streaming data.
Prototype
typedef
EFI_STATUS
(EFIAPI * EFI_USB_IO_ISOCHRONOUS_TRANSFER) (
IN EFI_USB_IO_PROTOCOL
*This,
IN UINT8 DeviceEndpoint,
IN OUT VOID *Data,
IN UINTN DataLength,
OUT UINT32 *Status
);
Parameters
This A pointer to the EFI_USB_IO_PROTOCOL instance. Type
EFI_USB_IO_PROTOCOL is defined in Section 14.2.5.
DeviceEndpoint The destination USB device endpoint to which the device request
is being sent.
DeviceEndpoint must be between 0x01 and
0x0F or between 0x81 and 0x8F, otherwise
EFI_INVALID_PARAMETER is returned. If the endpoint is not
an ISOCHRONOUS endpoint, EFI_INVALID_PARAMETER is
returned. The MSB of this parameter indicates the endpoint
direction. The number “1” stands for an IN endpoint, and “0”
stands for an OUT endpoint.
Data A pointer to the buffer of data that will be transmitted to USB
device or received from USB device.
DataLength The size, in bytes, of the data buffer specified by Data .
Status This parameter indicates the USB transfer status.