DisplayPort Stratix® 10 FPGA IP Design Example User Guide

ID 683887
Date 4/10/2024
Public
Document Table of Contents

2.1.2. DisplayPort 2.0 UHBR20 (20 Gbps) Data Rate Support

The DisplayPort 2.0 IP offers preliminary support for 20 Gbps (UHBR20). The current UHBR20 Design Example offers the following:

  • Support for static 20 Gbps Link Rate.
  • No backward compatibility with all other Link Rates.
  • Support for the DisplayPort SST parallel loopback without PCR variant.

The primary purpose of the UHBR20 Design Example is to ensure clean compile and timing at 20 Gbps. Intel has not performed a hardware test of UHBR20 due to unavailability of DP2.0 USB Type-C daughter cards in the market.

To support the DisplayPort 2.0 UHBR20 data rate:

  • Select MAX LINK RATE to 20 Gbps to enable DisplayPort 2.0.
  • Enable TX SUPPORT_IM_ENABLE to generate the design example variant without PCR.
  • Support for this 20 Gbps data rate requires a new transceiver refclk of 100 MHz.

Selecting MAX_LINK_RATE 20 Gbps fixes SYMBOLS_PER_CLOCK to 4. The DisplayPort Intel FPGA IP supporting the MAX_LINK_RATE 20 Gbps exports 64 bits data width of rx/tx_parallel_data per channel. The DisplayPort Intel FPGA IP remaps the parallel data width to 8B/10B channel coding data path and 128B/132B channel coding data path, respectively.

Selecting MAX_LINK_RATE 20 Gbps enables RX_GPU_MODE by default. The DisplayPort 2.0 sink is only supported in the GPU mode which requires the Nios® controller and Software Sink API.

In the software/dp_demo folder, rx_utils.c has updated the Sink DPCP capability register to support DisplayPort 2.0. The table below lists the DPCD registers.

Note: UHBR20 Design Example hardware support will be available in future.
Table 9.  DPCD Registers
DPCD Register Address Bit Description Design Example Default Value
0x0006h/0x2206h

MAIN_LINK_CHANNEL_CODING_CAP

  • 0 = Not supported.
  • 1 = Supported.
0

8b10b_DP_SUPPORTED

Mandated to be set to 1.

1’b1
1

128b132b_DP_SUPPORTED

Set for DPRXs that support 128b/132b DP Link Layer.

1’b1
0x2215h 128b132b_SUPPORTED_LINK_RATES

Valid only when the 128b132b_DP_SUPPORTED bit in the

MAIN_LINK_CHANNEL_CODING_CAP register is set (DPCD 0x2206h[1] = 1), for 128b/132b DP Link Layer.

0

10 Gbps per Lane Support

Indicates whether the link rate associated with UHBR10 is supported.

  • 0 = Not supported.
  • 1 = Supported. Support for this link rate is mandatory for the 128b/132b DP Link Layer-capable DP devices.

1’b1 (support

10Gbps)

1

20 Gbps per Lane Support

Indicates whether the link rate associated with UHBR20 is supported.

  • 0 = Not supported.
  • 1 = Supported. Highest link rate available.

Support is optional.

1’b1 (support 20 Gbps)
2

13.5 Gbps per Lane Support

Indicates whether the link rate associated with UHBR13.5 is supported.

  • 0 = Not supported.
  • 1 = Supported. Support is optional.

Note: Support for 13.5 Gbps/lane is optional, even for a DPRX that supports 20 Gbps/ lane.

1’b0 (not supported)
0x2216h

128b132b_DP_TRAINING_AUX_RD_INTERVAL

Valid only for 128b/132b DP Link Layer.

6:1

128b132b_DP_TRAINING_AUX_RD_INTER VAL

Updated through SCRs in DP v2.0 Errata E10.

Link Status/Adjust Request read interval during Main-Link training sequences.

The interval is

(128b132b_DP_TRAINING_AUX_RD_INTERVAL value + 1) ×

128b132b_DP_TRAINING_AUX_RD_INTERVAL_ UNIT

The maximum is 256 ms.

7’h3F (128ms selected)
0

128b132b_DP_TRAINING_AUX_RD_INTER VAL_UNIT

New through SCRs in DP v2.0 Errata E10.

  • 0 = 2 ms.
  • 1 = 1 ms.
1’b1