IDT Link Operation
PES16NT2 User Manual
3 - 5
April 15, 2008
Notes
Crosslink
Port A is an upstream port and only supports link training with a downstream port. Port C is an upstream
port that supports crosslink operation. This allows port C to link train and operate with any standard PCIe
upstream or downstream port. This feature enables the NTB port (i.e., port C) of two interconnected
PES16NT2 switches to link train and operate.
Link Status
Associated with each port is a Port Link Up (PxLINKUPN) status output. These outputs are provided on
GPIO alternate functions. The PxLINKUPN status outputs may be used to provide a visual indication of
system state, for error recovery or for debug. The PxLINKUPN output is asserted when the PCI Express
data link layer is up (i.e., when the LTSSM is in the L0, L0s, L1 or recovery states). When the data link layer
is down, this output is negated.
An interrupt may be generated by the external or internal NTB endpoints when a change occurs in link
status of any of the switch ports. Change in switch port link status may be selectively reported as an inter-
rupt (INTx or MSI) in the internal NTB domain, external NTB domain, or both.
Associated with each switch port are two status bits in the internal and external NTB endpoint INTSTS
registers. When the data link layer associated with a switch port transitions from a DL_Down state to a
DL_Up state, the corresponding PxLINKUP bit is set. When the data link layer associated with a switch port
transitions from a DL_Up state to a DL_Down state, the corresponding PxLINKDN bit is set. The interrupt
action (i.e., no action, INTx or MSI) taken when one of these bits is set is determined by the corresponding
field in the associated NTB endpoint’s INTCTL1 register.
Summary of Contents for 89HPES16NT2
Page 14: ...DT List of Figures PES16NT2 User Manual viii April 15 2008 Notes...
Page 20: ...IDT Register List PES16NT2 User Manual xiv April 15 2008 Notes...
Page 32: ...IDT PES16NT2 Device Overview PES16NT2 User Manual 1 12 April 15 2008 Notes...
Page 50: ...IDT Link Operation PES16NT2 User Manual 3 6 April 15 2008 Notes...
Page 62: ...IDT Power Management PES16NT2 User Manual 5 4 April 15 2008 Notes...
Page 78: ...IDT SMBus Interfaces PES16NT2 User Manual 6 16 April 15 2008 Notes...
Page 83: ...IDT NTB Upstream Port Failover PES16NT2 User Manual 7 5 April 15 2008 Notes...
Page 84: ...IDT NTB Upstream Port Failover PES16NT2 User Manual 7 6 April 15 2008 Notes...
Page 130: ...IDT Transparent Mode Operation PES16NT2 User Manual 9 44 April 15 2008 Notes...
Page 284: ...IDT Non Transparent Mode Operation PES16NT2 User Manual 10 154 April 15 2008 Notes...