Altera IP Compiler for PCI Express - Manual (Page 206)

12–4 Chapter 12: Error Handling
Transaction Layer Errors
IP Compiler for PCI Express User Guide August 2014 Altera Corporation
Unsupported requests for
root port
Uncorrectable fatal
This error occurs whenever a component receives an unsupported
request including:
■ Unsupported message
■ A type 0 configuration request TLP
■ A 64-bit memory transaction which the 32 MSBs of an address are
set to 0.
■ A memory transaction when the Memory Space Enable bit (bit [1] of
the PCI Command register at configuration space offset 0x4) is set to
0.
■ A memory transaction that does not match a Windows address
Completion timeout
Uncorrectable
(non-fatal)
This error occurs when a request originating from the application layer
does not generate a corresponding completion transaction layer packet
within the established time. It is the responsibility of the application layer
logic to provide the completion timeout mechanism. The completion
timeout should be reported from the transaction layer using the
cpl_err[0]
signal.
Completer abort (1)
Uncorrectable
(non-fatal) The application layer reports this error using the cpl_err[2]signal
when it aborts receipt of a transaction layer packet.
Unexpected completion
Uncorrectable
(non-fatal)
This error is caused by an unexpected completion transaction. The IP
core handles the following conditions:
■ The requester ID in the completion packet does not match the
configured ID of the endpoint.
■ The completion packet has an invalid tag number. (Typically, the tag
used in the completion packet exceeds the number of tags specified.)
■ The completion packet has a tag that does not match an outstanding
request.
■ The completion packet for a request that was to I/O or configuration
space has a length greater than 1 dword.
■ The completion status is Configuration Retry Status (CRS) in
response to a request that was not to configuration space.
In all of the above cases, the TLP is not presented to the application
layer; the IP core deletes it.
Other unexpected completion conditions can be detected by the
application layer and reported through the use of the cpl_err[2]
signal. For example, the application layer can report cases where the
total length of the received successful completions do not match the
original read request length.
Receiver overflow (1)
Uncorrectable
(fatal)
This error occurs when a component receives a transaction layer packet
that violates the FC credits allocated for this type of transaction layer
packet. In all cases the IP core deletes the TLP and it is not presented to
the application layer.
Flow control protocol error
(FCPE)
(1)
Uncorrectable
(fatal)
A receiver must never cumulatively issue more than 2047 outstanding
unused data credits or 127 header credits to the transmitter.
If Infinite credits are advertised for a particular TLP type (posted,
non-posted, completions) during initialization, update FC DLLPs must
continue to transmit infinite credits for that TLP type.
Table 12–4. Errors Detected by the Transaction Layer (Part 2 of 3)
Error Type Description