Hybrid Memory Cube Controller IP Core User Guide - Intel Stratix 10 Beta Version

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ID 683854
Date 8/08/2016
Public
Document Table of Contents
Document Table of Contents x
1. About the Hybrid Memory Cube Controller IP Core 2. Getting Started with the HMC Controller IP Core 3. Functional Description 4. HMC Controller IP Core Signals 5. HMC Controller IP Core Register Map 6. HMC Controller IP Core Stratix 10 Design Example A. HMC Controller IP Core User Guide Archives B. Additional Information
1. About the Hybrid Memory Cube Controller IP Core x
1.1. HMC Controller IP Core Supported Features 1.2. HMC Controller IP Core Supported HMC Transaction Types 1.3. Device Family Support 1.4. IP Core Verification 1.5. Performance and Resource Utilization 1.6. Device Speed Grade Support 1.7. Release Information
1.4. IP Core Verification x
1.4.1. Simulation
2. Getting Started with the HMC Controller IP Core x
2.1. Installing and Licensing Intel® FPGA IP Cores 2.2. Specifying IP Core Parameters and Options 2.3. HMC Controller IP Core Parameters 2.4. Files Generated for Intel FPGA IP Cores 2.5. Integrating Your IP Core in Your Design 2.6. Simulating Intel FPGA IP Cores
2.1. Installing and Licensing Intel® FPGA IP Cores x
2.1.1. Intel® FPGA IP Evaluation Mode
2.3. HMC Controller IP Core Parameters x
2.3.1. RX Mapping and TX Mapping Parameters
2.5. Integrating Your IP Core in Your Design x
2.5.1. Pin Constraints 2.5.2. Required External Blocks
2.5.2. Required External Blocks x
2.5.2.1. Adding the External PLL 2.5.2.2. Adding the External I2C Master Module
3. Functional Description x
3.1. High Level Block Diagram 3.2. Interfaces Overview 3.3. Clocking Structure 3.4. Initialization and Reset 3.5. M20K ECC Support 3.6. Flow Control 3.7. Error Detection and Management 3.8. Testing Features
3.2. Interfaces Overview x
3.2.1. Application Interfaces 3.2.2. HMC Interface 3.2.3. Interface to External I2C Master 3.2.4. Control and Status Register Interface 3.2.5. Status and Debug Interface 3.2.6. Transceiver Control Interfaces
3.2.6. Transceiver Control Interfaces x
3.2.6.1. External PLL Interface 3.2.6.2. Transceiver Reconfiguration Interface
4. HMC Controller IP Core Signals x
4.1. Application Interface Signals 4.2. HMC Interface Signals 4.3. Signals on the Interface to the I2C Master 4.4. Control and Status Register Interface Signals 4.5. Status and Debug Signals 4.6. Clock and Reset Signals 4.7. Transceiver Reconfiguration Signals 4.8. Signals on the Interface to the External PLL
4.1. Application Interface Signals x
4.1.1. Application Request Interface 4.1.2. Application Response Interface 4.1.3. HMC Controller IP Core Data Path Example
5. HMC Controller IP Core Register Map x
5.1. CONTROL Register 5.2. XCVR_STATUS Register 5.3. LANE_STATUS Register 5.4. LINK_STATUS Register 5.5. ERROR_RESPONSE Register 5.6. LIMIT_OUTSTANDING_PACKETS Register 5.7. Interrupt Related Registers 5.8. Error and Retry Statistics Registers
B. Additional Information x
B.1. HMC Controller IP Core User Guide Revision History
1. About the Hybrid Memory Cube Controller IP Core
2. Getting Started with the HMC Controller IP Core
3. Functional Description
4. HMC Controller IP Core Signals
5. HMC Controller IP Core Register Map
6. HMC Controller IP Core Stratix 10 Design Example
A. HMC Controller IP Core User Guide Archives
B. Additional Information

3.6. Flow Control

The HMC specification describes two possible flow control schemes for traffic between the host and the HMC memory device, token based flow control and Response Open Loop Mode.

In token-passing mode, the host sends information about its buffering capacity to the HMC device during transaction layer initialization. In Response Open Loop Mode, the host does not send information about its buffering capacity to the HMC device. Instead, the host only sends a request packet when it has room to receive the response at any time.

The HMC Controller IP core operates in Response Open Loop Mode. The IP core is designed to have the capacity to accept all response packets from the HMC device.

When user requests come in faster than the HMC Controller IP core can send them out on the HMC link, the HMC Controller IP core backpressures the application by deasserting the dp_req_ready signal.

In addition, the IP core supports the Limit Outstanding FLITs feature. You can turn on this feature to ensure that the IP core limits the number of outstanding FLITs in expected read responses. The IP core delays sending a request to the HMC if sending it would increase the number of pending response FLITs from the HMC above a user-specified threshold.

The Limit Outstanding FLITs feature limit the worst-case round-trip latency of packets in the system by avoiding the congestion that can occur when response packets have large payloads. A sequence of RD128 requests, for example, causes congestion in the response path. Designers building read-intensive, latency-sensitive applications can use the Limit Outstanding FLITs feature to improve latency and throughput.

Figure 15. Improving Latency and Throughput Flow Chart
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