Intel CONTROLLERS 413808 - Manual (Page 135)

Intel ® 413808 and 413812 I/O Controllers in TPER Mode
October 2007 Developer’s Manual
Order Number: 317805-001US 135
Address Translation Unit (PCI-X)—Intel
®
413808 and 413812
Table 24 details the PCI bus frequency initialization as a function of the PCI Bus
PCIXM1_100# and PCIXM2_100# reset strap, and the sampled secondary device
capabilities when operating in PCI-X mode.
Note: The PCI Bus PCI-X 100 MHz Enable strapping feature enables implementations to force
the PCI bus of 4138xx to operate at 100 MHz even with no standard provisions in the
PCI-X Protocol Addendum to the PCI Local Bus Specification, Revision 2.0 for reporting
device capability of 100 MHz operation.
When a card is plugged into a four slot PCI bus, a
P_PCIXCAP pull-down (R1)
strapping ensures that the bus runs at no greater than 66 MHz in PCI-X mode, and
grounding P_M66EN ensures that the bus runs at no greater than 33 MHz in PCI,
regardless of the reported downstream device capabilities.
When a card is plugged into a two slot secondary bus, the
PCIXM1_100# pull-down
strapping ensures that the bus runs at no greater than 100 MHz in PCI-X mode
regardless of the reported downstream device capabilities.
When a card is plugged into a single slot secondary (i.e., a segment that should be able
to run at 133 MHz), by strapping the PCIXM1_100# to 0b (as though it were a two
slot configuration), the bus operates at 100 MHz maximum
8
.
Table 24. PCI Bus Frequency Initialization
a
a. 4138xx does not support PCI-X 533 Mhz.
P_PCIXCAP P_MODE
2
P_M66EN PCIXM1_1
00#
PCIXM2_1
00#
PCI Bus
Mode
PCI Bus
Frequency PCSR[19:16 ]
< 0.11VCC - b
b. A ‘-’ in the table indicates the value is a don’t care for computing the bus mode/frequency. All signals must
still be pulled to a valid logic level.
Ground - - PCI 33 MHz 1111
< 0.11VCC -
Not
connected
- - PCI 66 MHz 1111
<0.6VCC &
>0.11 VCC
GND - - -
PCI-X
Mode 1
66 MHz 1110
<0.6VCC &
>0.11VCC
VCC - - GND
PCI-X
Mode 2
100 MHz
(PCI-X 200
MHz)
0101
<0.6VCC &
>0.11VCC
VCC - - VCC
PCI-X
Mode 2
133 MHz
(PCI-X 266
MHz)
0100
<0.89VCC &
>0.6VCC
- - - -
PCI-X
Mode 1
66 MHz 1110
>0.89VCC - - GND -
PCI-X
Mode 1
100 MHz 1101
>0.89VCC - - VCC -
PCI-X
Mode 1
133 MHz 1100
8. Adapters that report 133MHz PCI-X device capability with this PCIXM1_100# setting is limited
to 100MHz operation.