
IDT Link Operation
PES32NT24xG2 User Manual
7 - 14
January 30, 2013
Notes
The PES32NT24xG2 upstream ports request entry into L1 based on the criteria defined below. The L1
entry conditions must be met for 1 ms before the upstream port transitions the link to the L1 state. If these
conditions are met and the link is in the L0 or L0s states, then the hardware will request a transition to the
L1 state from its link partner. If the link partner acknowledges the transition, then the L1 state is entered.
Otherwise, L0s entry is attempted
1
.
The upstream port’s L1 entry conditions depend on the port’s operational mode, as follows.
A port configured in upstream switch port mode initiates L1 entry when all of the conditions listed below
are met:
–
L1 ASPM is enabled via the port’s PCIELCTL register.
–
All of the downstream switch ports in the partition which are not in a low power state (i.e., D3) and
whose link is not down are in the L1 state.
–
The port has no TLPs pending for transmission on the link. The port’s EFB is empty.
–
The port has no DLLPs pending for transmission.
–
The port’s receiver is idle (i.e., no TLPs or DLLPs are received) for the amount of time specified
above.
–
The port has accumulated enough flow-control header and data credits to transmit the largest
possible packet of each type (i.e., posted, non-posted, or completion).
A port configured in NT function mode or NT with DMA function mode initiates L1 entry when all of the
conditions listed below are met:
–
L1 ASPM is enabled in the PCIELCTL register of all functions of the port.
–
The port has no TLPs pending for transmission on the link.The port’s EFB is empty.
–
The port has no DLLPs pending for transmission.
–
The port’s receiver is idle (i.e., no TLPs or DLLPs are received) for the amount of time specified
above.
–
The port has accumulated enough flow-control header and data credits to transmit the largest
possible packet of each type (i.e., posted, non-posted, or completion).
A port configured in upstream switch port with NT function mode or upstream switch port with NT and
DMA function mode will enter L1 when all of the conditions listed below are met:
–
L1 ASPM is enabled in the PCIELCTL register of all functions of the port.
–
All of the downstream switch ports in the switch partition (i.e., associated with the PCI-to-PCI
bridge function) which are not in a low power state (i.e., D3) and whose link is not down are in the
L1 state.
–
The port has TLPs pending for transmission on the link. The port’s EFB is empty.
–
The port has no DLLPs pending for transmission.
–
The port’s receiver is idle (i.e., no TLPs or DLLPs are received) for the amount of time specified
above.
–
The port has accumulated enough flow-control header and data credits to transmit the largest
possible packet of each type (i.e., posted, non-posted, or completion).
L1 Exit Conditions
The L1 exit conditions depend on the port’s operational mode. A port configured in upstream switch port
mode initiates exit from L1 when either of the conditions listed below is met:
–
The port has a TLP scheduled for transmission on the link.
–
A downstream switch port in the switch partition has initiated exit from L1. The latency between
the downstream switch port’s initiated exit from L1 and the upstream port’s initiated exit from L1
must not exceed 1 µ s.
1.
L0s entry is subject to the rules specified in section L0s ASPM on page 7-12.
Summary of Contents for PCI Express 89HPES32NT24xG2
Page 20: ...IDT Table of Contents PES32NT24xG2 User Manual x January 30 2013 Notes...
Page 24: ...IDT List of Tables PES32NT24xG2 User Manual xiv January 30 2013 Notes...
Page 28: ...IDT List of Figures PES32NT24xG2 User Manual xviii January 30 2013 Notes...
Page 56: ...IDT PES32NT24xG2 Device Overview PES32NT24xG2 User Manual 1 20 January 30 2013 Notes...
Page 100: ...IDT Switch Core PES32NT24xG2 User Manual 4 22 January 30 2013 Notes...
Page 128: ...IDT Failover PES32NT24xG2 User Manual 6 4 January 30 2013 Notes...
Page 148: ...IDT Link Operation PES32NT24xG2 User Manual 7 20 January 30 2013 Notes...
Page 164: ...IDT SerDes PES32NT24xG2 User Manual 8 16 January 30 2013 Notes...
Page 170: ...IDT Power Management PES32NT24xG2 User Manual 9 6 January 30 2013 Notes...
Page 196: ...IDT Transparent Switch Operation PES32NT24xG2 User Manual 10 26 January 30 2013 Notes...
Page 244: ...IDT SMBus Interfaces PES32NT24xG2 User Manual 12 40 January 30 2013 Notes...
Page 247: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 3 January 30 2013 Notes...
Page 248: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 4 January 30 2013 Notes...
Page 330: ...IDT Switch Events PES32NT24xG2 User Manual 16 6 January 30 2013 Notes...
Page 342: ...IDT Multicast PES32NT24xG2 User Manual 17 12 January 30 2013 Notes...
Page 344: ...IDT Temperature Sensor PES32NT24xG2 User Manual 18 2 January 30 2013 Notes...
Page 384: ...IDT Register Organization PES32NT24xG2 User Manual 19 40 January 30 2013...
Page 492: ...IDT Proprietary Port Specific Registers PES32NT24xG2 User Manual 21 44 January 30 2013 Notes...
Page 588: ...IDT NT Endpoint Registers PES32NT24xG2 User Manual 22 96 January 30 2013 Notes...
Page 710: ...IDT JTAG Boundary Scan PES32NT24xG2 User Manual 25 12 January 30 2013 Notes...
Page 743: ...IDT Usage Models PES32NT24xG2 User Manual 26 33 January 30 2013 Notes...
Page 744: ...IDT Usage Models PES32NT24xG2 User Manual 26 34 January 30 2013 Notes...