6. Bridging
64
Tsi384 User Manual
May 5, 2014
Integrated Device Technology
www.idt.com
On PCIe Interface, the Tsi384 periodically conveys its available buffer space to the other end
component in terms of flow control credits using flow control packets. The Tsi384 advertises flow
control credits as per PCIe protocol requirements.
6.3
Buffer Size and Management
The Tsi384 provides sufficient buffering to satisfy PCIe bridging requirements. The Tsi384 does not
overcommit its buffers: it forwards requests onto the other side only when enough buffer space is
reserved to handle the returned completions.
The Tsi384 uses 2-KB retry buffering, which is large enough to ensure that under normal operating
conditions upstream traffic is never throttled. Ack latency value, internal processing delays, and
receiver L0s exit latency values, are considered for determining the Retry buffer size.
6.4
Assignment of Requestor ID and Tag
The Tsi384 assigns a unique transaction ID for all the non-posted requests forwarded to upstream
devices and unique sequence ID for all the posted and non-posted transactions forwarded to
downstream devices. The Tsi384 takes ownership of the upstream and downstream non-posted
transactions on behalf of original requestors, and stores the transaction-related state information needed
to return the completions to the original requesters. The action of replacing the original transaction’s
requester ID and/or Tag fields with the bridge’s own assigned values is referred to as taking ownership
of the transaction.
For upstream non-posted requests, the Tsi384 assigns the PCIe requester ID using its secondary bus
number and sets both the device number and function number fields to zero. For downstream
non-posted transactions, the Tsi384 assigns the PCI-X requester ID using its primary bus number,
device number and function number. For the upstream and downstream non-posted transactions, the
Tsi384 sets the Tag field to a request enqueued entry number. The Tsi384 forwards the downstream
posted transactions to PCI-X devices with the requester ID and Tag fields the same as that were
received with the request from the PCIe Interface.The Tsi384 attempts another posted request on the
PCI/X Interface only after the current transaction is committed on the PCI/X Interface, and thus,
eliminates the chance of sequence ID aliasing because the Tag[7:5] is non-zero.
Содержание TSI384
Страница 1: ... IDT Tsi384 PCIe to PCI Bridge User Manual May 5 2014 ...
Страница 10: ...Contents 10 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 36: ...2 Signal Descriptions 36 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 56: ...4 Addressing 56 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 62: ...5 Configuration Transactions 62 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 74: ...6 Bridging 74 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 78: ...7 PCI X Arbitration 78 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 128: ...11 Power Management 128 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 136: ...12 Serial EEPROM 136 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 142: ...13 JTAG 142 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 268: ...16 Packaging 268 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 276: ...276 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 280: ...Index 280 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...