IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 261 / 744

IDT Non-Transparent Switch Operation
PES32NT24xG2 User Manual 14 - 13 January 30, 2013
Notes
• The bus field is replaced by the captured bus number of the NT endpoint associated with the
partition of the translated TLP.
• The device and function fields are replaced by the value 0x3. This corresponds to device 0, func-
tion 3.
Figure 14.8 Request TLP Requester ID Translation
If the Bus Master Enable (BME) bit is cleared in the PCI Command (PCICMD) register of the NT
endpoint associated with the translated TLP (i.e., in the destination partition), then the request is treated as
an unsupported request by the NT endpoint that received the request (i.e., in the source partition).
Completion ID Translation
Completion TLPs contain both a requester ID field and a completer ID field. The completer ID field
defines the unique PCI Express identifier associated with the completer that generated the completion TLP.
When a completion TLP is received and claimed
1
by an NT endpoint the following processing is
performed.
– If the TLP’s requester ID function field matches the requester ID used by the NT function during
punch-through requests, and a punch-through configuration is in progress, the TLP is accepted
by the NT function and processed as described in section Punch-Through Configuration Requests
on page 14-18. Otherwise, if a punch-through configuration is not in progress, the TLP is handled
as an unexpected completion.
– If the TLP’s requester ID function field matches the NT function’s bus/device/function assignment
within the PCI Express hierarchy, then the TLP is handled as an unexpected completion by the
NT function. Refer to section Error Detection and Handling by the NT Function on page 14-25.
– Otherwise, the 8-bit value consisting of the device and function fields is extracted from the
requester ID field. The upper two bits are separated and the lower six bits form an NT Mapping
table entry index. If the upper two bits are 0b10 and the NT Mapping table entry index points to a
valid entry in the NT Mapping table, the processing described is performed. Otherwise, the TLP
is handled as an unexpected completion by the NT function.
The requester ID of the translated completion TLP is formed as follows.
– The requester ID bus field is replaced by the NT Mapping table bus field.
– The requester ID device field is replaced by the NT Mapping table device field.
– The requester ID function field is replaced by the NT Mapping table function field.
The completer ID of the translated completion TLP is equal to the bus, device, and function of the NT
endpoint associated with the partition of the translated completion TLP (i.e., the NT function that emits the
TLP).
1.
A completion TLP is claimed by the NT function when the TLP’s requester ID matches the NT function’s bus/
device/function assignment within the PCI Express hierarchy, when it matches a valid entry in the NT function’s
mapping table (as described below), or when it matches the NT function’s requester ID used for punch-through
requests (refer to section Punch-Through Configuration Requests on page 14-18).
Function
Request TLP Requester ID
Device Bus
0 2 3 7 8 15
Requester ID
Translation
Translated Requester ID
Destination NT Endpoint Captured Bus Number
8 15
0 0 0 0 0 0 1 1
0 7