
IDT Transparent Switch Operation
PES32NT24xG2 User Manual
10 - 3
January 30, 2013
Notes
When a CplDLk is received by the locked downstream switch port, it forwards the CplDLk transaction to
the upstream port and locks the upstream port so that all subsequent TLPs destined to the locked port from
other ports (except the locked downstream switch port) are blocked until the lock is released.
–
Bus locking only affects TLPs that map to VC0 at the egress port. TLPs that do not map to VC0
are not affected by the lock.
–
The CplDLk transaction obeys PCI ordering rules meaning that all queued posted requests at the
locked downstream switch port destined to the upstream port are completed prior to the CplDLk
being transmitted. The CplDLk is allowed to bypass queued non-posted requests.
When a CplDLk is returned by the locked downstream switch port and the upstream port becomes
locked, the partition is said to be ‘bus-locked’. While a partition is bus-locked, the following applies:
–
It is illegal to read or write any of the PCI Express configuration space headers in ports associated
with the partition since the switch can not generate a completion until the partition is unlocked. The
behavior of the partition is undefined when a partition’s PCI Express configuration space register
is read while the partition is bus-locked.
–
Any register in the ports associated with the partition may be read or written via the SMBus.
–
It is allowed for the root to perform subsequent reads from the locked device (e.g., a legacy
endpoint) by issuing a MRdLk requests to the locked device and receiving a CplDLk or CplLk
response from the locked device. These transactions do not change the state of the bus-locked
partition. Therefore, a CplLk completion received by the downstream switch port of a bus-locked
partition in no way “unlocks” the partition.
–
It is allowed for the root to perform subsequent writes to the locked device by issuing MWr
requests to the locked device. These transactions in no way change the state of the bus-locked
partition.
–
The locked upstream and downstream switch ports may generate messages (i.e., “insert
messages”). These messages include interrupt emulation messages and error messages. The
locked ports may also generate MSIs.
The behavior of a bus-locked partition is undefined when:
–
Any transaction other than a MWr, MRdLk, and Unlock message is received on the upstream port.
–
Any transaction other than a CplLk and a CplDLk is received on the locked downstream switch
port.
–
A MRdLk TLP is received on the partition’s upstream port destined to an unlocked downstream
switch port.
–
A TLP is received by the upstream port destined to an unlocked downstream switch port.
When an Unlock message is received on the partition’s upstream port, the partition is unlocked. This
causes the Unlock message to be forwarded to the locked downstream switch port and the unblocking of
transactions destined to the previously locked ports.
–
The unlock message obeys PCI ordering rules meaning that all queued posted requests from the
upstream port are completed prior to the switch becoming unlocked.
–
Unlocked ports ignore the reception of the unlock message.
Note that when a TLP received by a port is blocked from being forwarded due to a bus-locked partition,
the TLP is delayed until the partition is unlocked. If the partition is locked for an extended period, this may
cause TLPs to be discarded due to switch time-outs.
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...