IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 274 / 744

IDT Non-Transparent Switch Operation
PES32NT24xG2 User Manual 14 - 26 January 30, 2013
Notes
Some of the errors described below are marked as function-specific when the “function claims the TLP”.
A function claims a TLP in the following cases:
NT Endpoint function:
– Address Routed TLPs: The TLP address falls within the address space range(s) programmed in
the function’s base address registers (BARs).
– ID Routed TLPs: The TLPs requester ID matches any of the following:
• The NT function’s bus/device/function assignment within the PCI Express hierarchy.
• The requester ID used by the NT function for punch-through requests (i.e., refer to section
Punch-Through Configuration Requests on page 14-18)
• The upper two bits are 0b10 and the lower six bits point to a valid entry in the NT function’s
Mapping table.
– Implicit Route TLPs: Always.
PCI-to-PCI Bridge function
– Refer to section Error Detection and Handling by the PCI-to-PCI Bridge Function on page 10-11.
DMA function:
– Refer to section PCI Express Error Handling by the DMA Function on page 15-28.
For a port in Upstream Switch Port with NT Endpoint mode, the TLP is claimed when either one of its
two functions claims the TLP.
Physical Layer Errors
All physical layer errors are non-function specific. These errors are described in the error handling
section for the PCI-to-PCI bridge function. Refer to section Physical Layer Errors on page 10-11.
Data Link Layer Errors
All data link layer errors are non-function specific. These errors are described in the error handling
section for the PCI-to-PCI bridge function. Refer to section Data Link Layer Errors on page 10-12.
Transaction Layer Errors
Table 14.4 lists non-ACS error checks performed by the transaction layer and the action taken when an
error is detected. ACS error checks and handling are discussed in section Transaction Layer Error Pollution
on page 14-31.
For some errors, it is necessary to determine if the function that receives a TLP from the link is an “ulti-
mate receiver” or “intermediate receiver”. The NT function is always considered an ultimate receiver when
the TLP is received directly from the link. This applies to all TLPs, including NT multicast TLPs.
Per PCI Express Base Specification 2.1, transaction layer errors are ignored in cases where the error is
associated with a received packet for which the physical or data-link layers report an error. This prevents
error pollution across the stack layers. Within the transaction layer, there are error pollution rules that
resolve the cases where two or more errors are detected simultaneously. Refer to section Transaction
Layer Error Pollution on page 14-31 for details on transaction layer error pollution.