IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 282 / 744

IDT Non-Transparent Switch Operation
PES32NT24xG2 User Manual 14 - 34 January 30, 2013
Notes
When the PCI-to-PCI bridge function in Partition 2 detects the UR error, it logs it as such and generates
a completion TLP destined towards the NT Endpoint function associated with Partition 2. The completion
TLP is then transferred across the NTB and transmitted by the NT Endpoint in Partition 1 towards the initi-
ator of the request.
1
Note that each function that receives the TLP (i.e., NT function in partition 1 and PCI-to-PCI bridge func-
tion in partition 2) checks for UR errors. Also, notice that the request TLP logically stops at the PCI-to-PCI
bridge function in partition 2 since this function detects the UR error. For this example, error logging would
occur as shown in Table 14.7.
Figure 14.15 shows another example of an unsupported request condition for an inter-partition transfer.
In this case, a non-posted request TLP received by the downstream switch port in a first partition is logically
routed towards the NT endpoint in the same partition. The request TLP is then transferred across the NTB
to a second partition. The request is then URed by the PCI-to-PCI bridge function in the PES32NT24xG2
downstream switch port in the second partition.
Figure 14.15 Unsupported Request Example # 2
When the downstream switch port’s PCI-to-PCI bridge function in Partition 2 detects the UR error, it
generates a completion TLP destined towards the NT Endpoint function associated with Partition 2. The
completion TLP is then transferred across the NTB and sent by the NT Endpoint in Partition 1 towards the
initiator of the request. Again, note that each function that receives the TLP (i.e., NT function in partition 1,
1.
Note that the completion is guaranteed to cross the NTB since it corresponds to a request that had previously
crossed the NTB. That is, the completion’s destination ID will hit a valid entry in the NT Mapping table.
Function Error Logging
Upstream PCI-to-PCI Bridge (Parti-
tion 2) Refer to row corresponding to ‘Unsupported
Request’ error in
Table 10.9
NT Endpoint (Partition 2) Refer to row corresponding to ‘Completion with
UR status received’ in Table 14.4
NT Endpoint (Partition 1) No error logged.
Table 14.7 Error Logging at Each Function for UR Example # 1
Partition 1 – Virtual PCI Bus
P2P
Bridge
Upstream
Port
P2P
Bridge
P2P
Bridge
Upstream
Port
Partition 2 – Virtual PCI Bus
P2P
Bridge
P2P
Bridge
P2P
Bridge
NT
Endpoint
NT
Endpoint
Downstream Ports
Non Transparent
Interconnect
Non-Posted Request
UR Completion