6. Bridging
67
Tsi384 User Manual
May 5, 2014
Integrated Device Technology
www.idt.com
6.7
Forwarding of PCI to PCIe
The Tsi384 forwards posted and non-posted requests and downstream read completions to PCIe
devices, and stores the non-posted requests’ state information to return the delayed completions to the
requester.
6.7.1
PCI Memory Write Request
The Tsi384 translates the received Memory Write (MW) and Memory Write and Invalidate (MWI)
transactions into PCIe Memory Write Requests. The Tsi384 uses a 4-KB posted buffer to post the
received transactions. Write requests are fragmented if one of the following PCIe constraints is met:
•
Address plus length crosses the 4-KB boundary
•
Burst writes with discontinuous byte enables
•
Payload size exceeds MAX_PAY_SIZE in
“PCIe Device Control and Status Register”
The Tsi384 terminates a posted transaction with retry only if the buffers are filled with previously
received memory requests, or if the bridge is locked from the PCIe side (see
).
6.7.2
PCI Non-posted Requests
The Tsi384 processes all non-posted transactions as delayed transactions. The Tsi384 first terminates
the received non-posted transaction with retry and then forwards it onto the PCIe Interface. The Tsi384
stores the request-related state information while forwarding the request onto the PCIe Interface. This
information tracks the requests repeated by the master and returned completions for the request. Since
PCI read requests do not specify the amount of data to be read, the Tsi384 uses a programmable
prefetch algorithm to determine the amount of data to be read on behalf of the original requester. The
Tsi384 does not attempt to prefetch past the 4-KB address boundary on behalf of the original requester.
The Tsi384 stores the returned completion until the PCI requester repeats the initial request and
terminates the delayed transaction. If short-term caching is enabled (see STC_EN in
Miscellaneous Control and Status Register”
), the Tsi384 responds to subsequent requests with the
incremental addresses issued by the master until the programmed number of data bytes are transferred
to the master or the short-term discard timer is expired (see ST_DIST_EN in
The Tsi384 enqueues up to eight requests and issues the initial requests on the PCIe Interface in the
order they were received; however, the ordering is not guaranteed for the subsequent requests of
decomposed transactions.
The Tsi384 discards the enqueued delayed request if the requested data is not returned before the
completion timeout is expired (see
), and returns a delayed completion
with target abort to the requester (see DISCARD2 in
“PCI Bridge Control and Interrupt Register”
delayed completion is discarded if the requester does not repeat the initial request or if the requester
disconnects the delayed completion after few data bytes are transferred.
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 ...