R-tile Avalon® Streaming Intel® FPGA IP for PCI Express* User Guide

ID 683501
Date 3/28/2022
Public

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5.2.3.13. Power Management

Table 98.  Power Management
Parameter Value Default Value Description
Endpoint L0s acceptable latency

Maximum of 64 ns

Maximum of 128 ns

Maximum of 256 ns

Maximum of 512 ns

Maximum of 1 us

Maximum of 2 us

Maximum of 4 us

No limit

Maximum of 64 ns

This design parameter specifies the maximum acceptable latency that the application layer can tolerate for any link between the device and the root complex to exit the L0s state. It sets the read-only value of the Endpoint L0s acceptable latency field of the Device Capabilities Register (0x084).

This Endpoint does not support the L0s or L1 states. However, in a switched system, there may be links connected to switches that have L0s and L1 enabled. This parameter is set to allow system configuration software to read the acceptable latencies for all devices in the system and the exit latency for each link to determine which links can enable Active State Power Management (ASPM).

This setting is disabled for Root Ports.

The default value of this parameter is 64 ns. This is the safest setting for most designs.

Endpoint L1 acceptable latency

Maximum of 1 us

Maximum of 2 us

Maximum of 4 us

Maximum of 8 us

Maximum of 16 us

Maximum of 32 us

Maximum of 64 us

No limit

Maximum of 1 us

This value indicates the acceptable latency that an Endpoint can withstand in the transition from the L1 state to L0 state. It is an indirect measure of the Endpoint’s internal buffering. It sets the read-only value of the Endpoint L1 acceptable latency field of the Device Capabilities Register.

This Endpoint does not support the L0s or L1 states. However, a switched system may include links connected to switches that have L0s and L1 enabled. This parameter is set to allow system configuration software to read the acceptable latencies for all devices in the system and the exit latency for each link to determine which links can enable Active State Power Management (ASPM).

This setting is disabled for Root Ports.

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