Agilex™ 7 M-Series Known Issue List

ID 851750
Date 4/18/2025
Public
Document Table of Contents

2.2.7. LPDDR5 and DDR5 reduced sequential write/read bandwidth when using Fabric Sync Fabric direct mode in x16 2-channel configuration

Description

In LPDDR5 and DDR5 memory interfaces, when using x16 2-channel configuration for long burst sequential access during write or read operations, in fabric sync access mode, performance is limited to 50% per read/write sub-channel.

There is no performance degradation in the following configurations:
  • LPDDR5 x16 1-channel when placed in the bottom GPIO-B sub-bank
  • DDR5 x16 1-channel
  • All impacted configurations, listed below, with random access and in sequential access with mixed read-write traffic
  • In all supported configurations with NoC access mode

Impacted configurations:

  • DDR5 x32 configuration in DIMM or component configuration
  • LPDDR5 x32 configuration
  • LPDDR5 and DDR5 x16 2-channel configuration only with Fabric Sync
  • LPDDR5 x32 1-channel
  • LPDDR5 x16 1-channel when placed in the top GPIO-B sub-bank

Workaround

We recommend using the Fabric Async mode for the impacted configurations. You can access via NoC or Fabric Async mode with the user clock set to ¼ of the memory clock which provides full sequential bandwidth on a single sub-channel.

Status

Table 33.  Device Status Table
Devices Affected Planned Fix
  • AGMx0xxR47Axxxx
  • AGMx0xxR31Bxxxx
None