Intel Extensible Firmware Interface - Manual (Page 564)

Extensible Firmware Interface Specification
14-24 12/01/02 Version 1.10
IsochronousCallback The Callback function. This function is called if the requested
isochronous transfer is completed. Refer to Section 2.5.3 of
EFI1.1 USB Driver Model, version 0.7.
Context Data passed to the IsochronousCallback function. This is
an optional parameter and may be NULL .
Description
This is an asynchronous type of USB isochronous transfer. If the caller submits a USB isochronous
transfer request through this function, this function will return immediately. When the isochronous
transfer completes, the
IsochronousCallback function will be triggered, the caller can know
the transfer results. If the transfer is successful, the caller can get the data received or sent in this
callback function.
The target endpoint is specified by DeviceAddress and EndpointAddress . Isochronous
transfers are used when working with isochronous date. It provides periodic, continuous
communication between the host and a device.
EFI_INVALID_PARAMETER is returned if one of the following conditions is satisfied:
1. Data is NULL .
2. DataLength is 0.
3. MaximumPacketLength is larger than 1023.
Status Codes Returned
EFI_SUCCESS The asynchronous isochronous transfer was completed successfully.
EFI_OUT_OF_RESOURCES The asynchronous isochronous transfer could not be submitted due to
lack of resource.
EFI_INVALID_PARAMETER Some parameters are invalid. The possible invalid parameters are
described in “Description” above.