IDT Link Operation
Link Retraining
PES12N3 User Manual
3 - 3
June 7, 2006
Notes
When link training occurs, the corresponding lane reversal bits in the PA_SWCTL register are examined.
If a bit is set, then the lanes associated with that link are revered. This mechanism may be used to configure
lane reversal via the serial EEPROM, slave SMBus, or root.
Link Retraining
Link retraining should not cause either a downstream component or an upstream component to reset or
revert to default values.
Link Down
When a link goes down, all TLPs received by the port and queued in the switch are discarded and all
TLPs received by other ports and destined to the port whose link is down are treated as Unsupported
Requests (UR). While a link is down, it is possible to perform configuration read and write operations to the
PCI-PCI bridge associated with the link. However, it is possible to lose configuration read or write comple-
tions when TLPs queued in the switch are discarded.
1
If this occurs, the root’s completion timer associated
with the transaction(s) will time-out and the transaction will be retired.
When a link comes up, flow control credits for the configured size of the IFB FIFOs are advertised.
Slot Power Limit Support
The Set_Slot_Power_Limit message is used to convey a slot power limit value from a downstream
switch port (i.e., ports B or C) to the upstream port of a connected device or switch. A
Set_Slot_Power_Limit message is set by downstream switch ports when either of the following events
occurs:
–
A configuration write is performed to the corresponding PCIESCAP register when the link associ-
ated with the downstream port is up.
–
A link associated with the downstream port transitions from a non-operational state to an opera-
tional (i.e., up) state.
1.
In the case of a configuration write that causes link retraining or a secondary bus reset, a completion corre-
sponding to the configuration write is always returned and never lost.
Summary of Contents for 89HPES12N3
Page 10: ...IDT Table of Contents PES12N3 User Manual iv June 7 2006 Notes...
Page 14: ...IDT List of Figures PES12N3 User Manual viii June 7 2006 Notes...
Page 36: ...IDT Clocking Reset and Initialization Reset PES12N3 User Manual 2 8 June 7 2006 Notes...
Page 40: ...IDT Link Operation Slot Power Limit Support PES12N3 User Manual 3 4 June 7 2006 Notes...
Page 50: ...IDT Switch Operation Switch Core Errors PES12N3 User Manual 4 10 June 7 2006 Notes...
Page 54: ...IDT Power Management Active State Power Management PES12N3 User Manual 5 4 June 7 2006 Notes...
Page 62: ...IDT Hot Plug and Hot Swap Hot Swap PES12N3 User Manual 6 8 June 7 2006 Notes...
Page 78: ...IDT SMBus Interfaces Slave SMBus Interface PES12N3 User Manual 7 16 June 7 2006 Notes...
Page 148: ...IDT Test and Debug SerDes Test Clock PES12N3 User Manual 10 6 June 7 2006...
Page 158: ...IDT JTAG Boundary Scan Usage Considerations PES12N3 User Manual 11 10 June 7 2006 Notes...