PI7C21P100B Datasheet, PDF (58/79 Pages) Pericom Semiconductor Corporation – 2-PORT PCI-X TO PCI-X BRIDGE

PI7C21P100B
2-PORT PCI-X TO PCI-X BRIDGE
The below settings are the only allowed values. Other settings are not valid and will result in
smaller retry counts. When the counter expires, the bridge discards the requested transaction
on the secondary bus and issues SERR# on the primary bus if enabled.
0000 0000:
8000 0000:
0100 0000:
0001 0000:
0000 0100:
No expiration limit
Allow 2G retries before expiration
Allow 16M retries before expiration
Allow 64K retries before expiration
Allow 256 retries before expiration
8.1.45
DISCARD TIMER CONTROL REGISTER – OFFSET 68h
BIT
FUNCTION
TYPE DESCRIPTION
7:4
RESERVED
RO
Reserved. Returns 0000 when read.
3
Primary Discard Timer RW
Primary Discard Timer Short Duration
Short Duration
0: Use bit[24] offset 3Ch of the bridge control register to indicate
how many PCI clocks should be allowed before the primary discard
timer expires.
1: 64 PCI clocks allowed before the discard time expires.
Reset to 0
2
Secondary Discard
RW
Secondary Discard Timer Short Duration
Timer Short Duration
0: Use bit[25] offset 3Ch of the bridge control register to indicate
how many PCI clocks should be allowed before the secondary
discard timer expires.
1: 64 PCI clocks allowed before the secondary discard timer expires.
Reset to 0
1
Primary Discard Timer RW
Primary Discard Timer Disable
Disable
0: Enable the primary discard timer in conjunction with bit[27] offset
3Ch of the bridge control register
1: Disable the primary discard timer in conjunction with bit[27]
offset 3Ch of the bridge control register
Reset to 0
0
Secondary Discard
RW
Secondary Discard Timer Disable
Timer Disable
0: Enable the secondary discard timer in conjunction with bit[27]
offset 3Ch of the bridge control register
1: Disable the secondary discard timer in conjunction with bit[27]
offset 3Ch of the bridge control register
Reset to 0
8.1.46
RETRY AND TIMER STATUS REGISTER – OFFSET 6Ch
BIT
FUNCTION
TYPE DESCRIPTION
7:4
RESERVED
RO
Reserved. Returns 0000 when read.
3
Primary Discard Timer RW
Primary Discard Timer Status
Status
0: The primary discard timer has not expired since the last reset.
1: The primary discard timer has expired since the last reset.
Reset to 0
2
Secondary Discard
RW
Secondary Discard Timer Status
Timer Status
0: The secondary discard timer has not expired since the last reset.
1: The secondary discard timer has expired since the last reset.
Reset to 0
1
Primary Retry Counter RW
Primary Retry Counter Status
Status
0: The primary retry counter has not expired since the last request.
1: The primary retry counter has expired since the last request.
Reset to 0.
0
Secondary Retry
RW
Secondary Retry Counter Status
Counter Status
0: The secondary retry counter has not expired since the last request.
1: The secondary retry counter has expired since the last request.
Reset to 0.
Page 58 of 79
November 2005 – Revision 1.02