Intel CONTROLLERS 413808 - Manual (Page 262)

Intel
®
413808 and 413812—Address Translation Unit (PCI Express)
Intel ® 413808 and 413812 I/O Controllers in TPER Mode
Developer’s Manual October 2007
262 Order Number: 317805-001US
3.8.1.2 Inbound Non Posted Queue Structure
The inbound read queues are responsible for retrieving data from local memory and
returning it to the PCI Express Link in response to a read transaction initiated from a
PCI master. Up to 8 non posted transactions can be held in the INPQ. The read data is
returned through OCPLDQ
For Configuration and I/O writes, both the header and data are placed in the INPQ.
Configuration and I/O transactions always utilize the 3DW header and the data for the
write transactions is always 1DW. So the data can be placed in the same queue as the
header. The advantage to this is the NPD (non-posted data) credits can be advertised
as infinite and the header credits prevents overrunning the INPQ.
Read requests are fragmented into 1K aligned requests before issuing to the internal
bus/
3.8.1.3 Inbound Completion Queue Structure
The inbound completion queue provides insures space for all outstanding outbound
read requests. This queue is 4KB in size and is used to order the completion data
before returning it to the internal bus. When an outbound internal bus request is
fragmented into multiple PCI Express request this queue ensures that the data is
returned in order to the internal requesting agent.
3.8.1.4 Inbound Transaction Queues Command Translation Summary
Table 127. PCI to Internal Bus Command Translation for All Inbound Transactions
PCI Express TLP Internal Bus Command
Memory Read Read
Memory Read - Locked none - Unsupported Request
Memory Write Write
I/O Read Read
I/O Write Write
Configuration Read Type 0 Read
Configuration Write Type 0 Write
Configuration Read Type 1 none - Unsupported Request
Configuration Write Type 1 none - Unsupported Request
Message none - Handled by express message unit
Message with Data none - Handled by EMU
Message Advanced Switch none - Unsupported Request
Message Advanced Switch with Data none - Unsupported Request
Completion without Data
Completion with Data
Completion - Locked
without Data (error condition)
none
Completion - Locked
with Data
Others (reserved encodings)