Achronix ACE Version 5.0 User Manual
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Chapter 3. Concepts
Enable L1 ASPM
Support
Active State Power Management (ASPM) Support
L1 Entry Time (hex)
Number of microseconds of idle time to wait before requesting entry to ASPM
L1 (used by Upstream Ports Endpoint/Upstream Switch - only). Idle time is
defined as no TLP or ACK/NAK DLLP transmissions. PCIe Specification does
not define a minimum or maximum value. Too low a value risks wasting link
bandwidth due to ASPM L1 entry/exit latencies. Too high a value will reduce
ASPM L1 power savings. Only used if Enable L1s Power Mgmt is set. 0 is a
special case and selects 1000 uS (0x3e8)
Endpoint L1
Acceptable Latency
From PCI Express Base Specification, Rev 2.1 section 7.8.3: This field indicates
the acceptable latency that an Endpoint can withstand due to the transition
from L1 state to the L0 state. It is essentially an indirect measure of the
Endpoint’s internal buffering
L1 Exit Latency
Length of time required to complete transition from L1 to L0
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UG001 Rev. 5.0 - 5th December 2012