Endpoint Context Data Structure and State Diagram

Zynq UltraScale+ Device Technical Reference Manual (UG1085)

Document ID
UG1085
Release Date
2022-09-15
Revision
2.3 English

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.

Table 31-4:      Endpoint (EP) Data Structure

31

 

 

 

 

 

 

24

23

 

 

 

 

 

 

16

15

14

 

 

 

10

9

8

7

6

5

4

3

2

1

0

 

Maximum ESIT Payload High

Interval

LSA

MaxPStreams

Multi

RsvdZ

EP State

03-00H

Maximum Packet Size

Maximum Burst Size

HID

RsvdZ

EP Type

CERR

RsvdZ

07-04H

Transfer Ring Dequeue Pointer Low

RsvdZ

DCS

0B-08H

Transfer Ring Dequeue Pointer High

0F-0CH

Maximum ESIT Payload Low

Average TRB Length

13-10H

xHCI Reserved (Rsvd0)

17-14H

xHCI Reserved (Rsvd0)

1B-18H

xHCI Reserved (Rsvd0)

1F-1CH

Figure 31-5:      Endpoint Structure State Machine

X-Ref Target - Figure 31-5

X15501-endpoint-structure-state-machine.jpg

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.

Figure 31-6:      Formation of Transfer Rings

X-Ref Target - Figure 31-6

X15502-transfer-rings.jpg

The Table: Normal TRB Data Structure to Table: Event Data TRB Data Structure represent the various TRBs.