PI7C9X20404SLCFDE Pericom Semiconductor, PI7C9X20404SLCFDE Datasheet - Page 19

• Manufacturer Part Number: PI7C9X20404SLCFDE
• Description: IC PCIE PACKET SWITCH 128LQFP
• Manufacturer: Pericom Semiconductor
• Series: SlimLine™r

Specifications of PI7C9X20404SLCFDE

• Applications: Data Transport
• Interface: Advanced Configuration Power Interface (ACPI)
• Package / Case: 128-LQFP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -

5.5 TC/VC MAPPING
The 3-bit TC field defined in the header identifies the traffic class of the incoming packets. To enable the
differential service, a TC/VC mapping table at destination port that is pre-programmed by system software or
EEPROM pre-load is utilized to cast the TC labeled packets into the desired virtual channel. Note that all the traffic
classes are mapped to VC0, since only VC0 is available on the Switch. After the TC/VC mapping, the receive block
dispatches the incoming request, completion, or data into the VC0 queues.
5.6
In PCI Express, it defines six different packet types to represent request, completion, and data. They are respectively
Posted Request Header (PH), Posted Request Data payload (PD), Non-Posted Request Header (NPH), Non-Posted
Data Payload (NPD), Completion Header (CPLH) and Completion Data payload (CPLD). Each packet with
different type would be put into a separate queue in order to facilitate the following ordering processor. Since NPD
usually contains one DW, it can be merged with the corresponding NPH into a common queue named NPHD.
5.6.1
PH queue provides TLP header spaces for posted memory writes and various message request headers. Each header
space occupies sixteen bytes to accommodate 3 DW or 4 DW headers.
5.6.2
PD queue is used for storing posted request data. If the received TLP is of the posted request type and is determined
to have payload coming with the header, the payload data would be put into PD queue.
5.6.3 NPHD
NPHD queue provides TLP header spaces for non-posted request packets, which include memory read, IO read, IO
write, configuration read, and configuration write. Each header space takes twenty bytes to accommodate a 3-DW
header, s 4-DW header, s 3-WD header with 1-DW data, and a 4-DW header with 1-DW data.
5.6.4 CPLH
CPLH queue provides TLP header space for completion packets. Each header space takes twelve bytes to
accommodate a 3-DW header. Please note that there is no 4-DW completion headers.
5.6.5 CPLD
CPLD queue is used for storing completion data. If the received TLP is of the completion type and is determined to
have payload coming with the header, the payload data would be put into CPLD queue.
July 2009 – Revision 1.2
Pericom Semiconductor
QUEUE
PH
PD
Page 19 of 77
4Port-4Lane PCI Express® Switch
SlimLine
PI7C9X20404SL
Datasheet
TM
Family