
IDT Power Management
PES32NT24xG2 User Manual
9 - 5
January 30, 2013
Notes
–
When PME_TO_Ack aggregation is abandoned, the PES32NT24xG2 makes no attempt to
abandon the PME_Turn_Off and PME_TO_Ack protocol on downstream switch ports. Devices
downstream of the switch are allowed to respond with a PME_TO_Ack and transition to L2/L3
Ready. When a TLP is received that needs to be routed to the downstream switch port’s link, then
the switch transitions the link to Detect and then to L0. Once the link reaches L0, the TLP is trans-
mitted on the downstream switch port.
NT Function Mode or NT with DMA Function Mode
When a port configured in NT function mode or NT with DMA function mode receives a PME_Turn_Off
message, it immediately generates a PME_TO_Ack message for transmission on its link. After transmitting
the PME_TO_Ack message, the port transitions its link state to L2/L3 Ready.
• In the PES32NT24xG2, the link is considered down in the L2/L3 Ready state (see section Link
States on page 7-9). This allows a power management turn-off event in a partition to be signaled
via the event signaling mechanism (see Chapter 16, Switch Events).
All TLPs received by the port after the PME_Turn_Off message is received (before the link is placed in
L2/L3 Ready) are discarded. Note that it is the responsibility of software (e.g., the NT driver) to ensure that
inter-partition communication associated with the NT function is properly quiesced prior to initiating the
PME_Turn_Off / PME_TO_Ack handshake.
Finally, note that the DMA function does not automatically quiesce traffic as a result of the
PME_Turn_Off / PME_TO_Ack handshake on the port. It is the responsibility of software (e.g., the DMA
driver) to ensure that the DMA function is properly quiesced prior to initiating the PME_Turn_Off /
PME_TO_Ack handshake.
Upstream Switch Port with NT and/or DMA Function Mode
When a port configured in upstream switch port with NT function mode, upstream switch port with DMA
function mode, or upstream switch port with NT and DMA function mode receives a PME_Turn_Off
message, the port transmits a PME_TO_Ack message when the PCI-to-PCI bridge function has completed
PME_TO_Ack aggregation, as described in section Upstream Switch Port or Downstream Switch Port
Mode on page 9-4 above.
After the PME_Turn_Off message is received, but before the PME_TO_Ack message has been sched-
uled for transmission, the reception of a TLP by the port causes PME_Turn_Off aggregation to be aban-
doned. If the TLP that causes PME_TO_Ack aggregation to be abandoned targets a switch function (i.e.,
PCI-to-PCI bridge, NT, or DMA), then the targeted function responds to the TLP normally.
Once the PME_TO_Ack message has been scheduled for transmission by the port, the port discards all
received TLPs. After transmitting the PME_TO_Ack message, the port transitions its link state to L2/L3
Ready. In the PES32NT24xG2, the link is considered down in the L2/L3 Ready state (see section Link
States on page 7-9). This allows a power management turn-off event in a partition to be signaled via the
Event Signaling mechanism described in Chapter 16, Switch Events.
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...