82870P2P64H2 Datasheet, PDF (147/217 Pages) –

Functional Description
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4.3.1.9
4.3.1.10
PCI Card Initialization
The hot plug controller and the system board must guarantee that PCI-X cards are properly
initialized when brought out of reset. PCI cards may have to sample the REQ64# line when
PCIRST# is deasserted to determine if they are on a 64-bit data bus or not, as well as the M66EN
pin to determine the speed of the PCI bus. PCI-X cards are additionally required to sample the
DEVSEL#, STOP#, and TRDY# pins to determine the PCI-X mode of the bus. The state of all
these signals together is called the initialization pattern when PCIRST# is deasserted.
When the hot plug controller is operating in CBF mode, there is no additional hardware required
to guarantee that the PCI-X cards will correctly sample the initialization pattern. The P64H2 will
begin driving the initialization pattern when the HPx_SOL signal goes low during the bus enable
step of the CBF power up sequence. P64H2 will guarantee that this pattern is held active through
the rising edge of HPx_SOLR, which will deassert PCIRST# to the slot. The PCI-X card will see
the pattern driven on its pins 330ns before the rising edge of the card’s PCIRST#, which is the time
between the slot’s bus enable and reset deassertion.
When the hot plug controller is operating in CBL mode, the board designer must add additional
logic to guarantee that the PCI-X cards will see the proper initialization pattern on the rising edge
of PCIRST#, and that the pattern meets the timings specified in the PCI Local Bus Specification,
Revision 2.2, and the PCI-X Addendum to the PCI Local Bus Specification, Revision 1.0.
Changing PCI Frequency/Modes
When HPx_SLOT[2:0] for a PCI interface is not 000, the PCI bus is expected to power up
operating at 33 MHz PCI. If software determines that the inserted slots are PCI-X capable, or PCI
capable at 66 MHz, the PCI bus may be reset to operate in the new mode.
Intel^® 82870P2 P64H2 Datasheet
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