Bulk mode bandwidth is not guaranteed. For guaranteed bandwidth, Isochronous mode transfers should be considered. However, to provide optimal throughput, set the buffering for 4x512 or quad buffering. Indeed, for many microframes, the host can schedule more than 4 Bulk packet transfers or it may schedule less than the 4 Bulk transfers. Although Bulk transfers can be bursty in nature, the data accuracy is guaranteed, since packet retries are performed on transfer errors.Endpoints 4 and 8 can only be 512 double buffered. Endpoints 2 and 6 are selectable. The EZ-USB Technical Reference Manual can be downloaded at the following URL: http://www.cypress.com/?rID=38232
The application note Streaming Data Through Isochronous/Bulk Endpoints on EZ-USB FX2(TM) and EZ-USB FX2LP(TM) - AN4053 provides information on streaming data through bulk/isochronous endpoint.