Table: Endpoint (EP) Data Structure refers to the Endpoint data structure that contains information for each Endpoint in a device. This Figure represents the Endpoint state machine and error handling.
The interface consists of transfer request buffers (TRBs) that are managed in TRB rings. All transfer types (ISOC, interrupt, Control, Bulk, also command, events) use the same basic TRB structure. TRBs also support scatter/gather operations. Any transfer (command, data, event) between the software and the controller are moved as blocks of data. These blocks are called transfer request blocks (also TRBs). Based on the type of data movement, the specification defines various TRBs.
This Figure represents the formation of transfer rings from an atomic buffer level.