3. Data Path
43
Tsi384 User Manual
May 5, 2014
Integrated Device Technology
www.idt.com
The Tsi384 uses flow control buffers in the PCI Core for three categories of downstream traffic. The
amount of flow control buffer space availability is conveyed to the other end of the component using
flow control credits. The Tsi384 advertises infinite credits for completions as it ensures enough buffer
space is available to store the returned completion data before initiating a read request. The Tsi384
advertises initial flow control credits as follows. Each credit of data is 16 bytes.
3.5
Prefetching Algorithm
To optimize data throughput, the Tsi384 prefetches read data from a target device when the
PCI/X Interface is configured in PCI mode. The Tsi384 does not prefetch additional read data when
operating in PCI-X mode because the amount of data requested is specified in the byte count. The
Tsi384 prefetches the data by default for the transaction that uses Memory Read Line or Memory Read
Multiple command. The Tsi384 does not prefetch the data by default for the transaction that uses the
memory read command since the bridge does not know whether or not the transaction address falls in
prefetchable region.
The prefetch algorithm is configured for various commands as follows:
•
Memory read – Controlled by P_MR, MRL_66 and MRL_33 of the
.
The default value of these bits indicates that either one Dword in 32-bit bus mode or two Dwords
in 64-bit bus mode is prefetched.
•
Memory read line – Controlled by P_MRL, MRL_66 and MRL_33 of the
. The default value of these bits indicates that either 128 bytes in 32-bit bus mode or
256 bytes in 64-bit bus mode is prefetched. The Tsi384 prefetches one cacheline if P_MRL is set to
0.
•
Prefetch algorithm for memory read multiple command is controlled by P_MRM, MRM_66 and
MRM_33 of the
. The default value of these bits indicates that either
256 bytes in 32-bit bus mode or 384 bytes in 64-bit bus mode is prefetched. The Tsi384 prefetches
two cachelines if P_MRM is set to 0.
Table 8: Initial Credit Advertisement
Credit Type
Initial Advertisement
Posted Header (PH)
0x08
Posted Data (PD)
0x020
Non-Posted Header (NPH)
0x04
Non-Posted Data (NPD)
0x01
Completion Header (CPLH)
0x00 (Infinite)
Completion Data (CPLD)
0x000 (Infinite)
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 ...