PI7C8150AND datasheet(56/111 Pages) PERICOM

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PI7C8150A

2-PORT PCI-TO-PCI BRIDGE

Page 56 of 111

APRIL 2006 – Revision 1.1

For downstream delayed write transactions, when the parity error is detected on the

initiator bus and PI7C8150A has write status to return, the following events occur:

PI7C8150A first asserts P_TRDY_L and then asserts P_PERR_L two cycles later, if

the primary interface parity-error-response bit is set in the command register.

PI7C8150A sets the primary interface parity-error-detected bit in the status register.

Because there was not an exact data and parity match, the write status is not returned

and the transaction remains in the queue.

Similarly, for upstream delayed write transactions, when the parity error is detected on the

initiator bus and PI7C8150A has write status to return, the following events occur:

PI7C8150A first asserts S_TRDY_L and then asserts S_PERR_L two cycles later, if

the secondary interface parity-error-response bit is set in the bridge control register

(offset 3Ch).

PI7C8150A sets the secondary interface parity-error-detected bit in the secondary

status register.

Because there was not an exact data and parity match, the write status is not returned

and the transaction remains in the queue.

For downstream transactions, where the parity error is being passed back from the target

bus and the parity error condition was not originally detected on the initiator bus, the

following events occur:

PI7C8150A asserts P_PERR_L two cycles after the data transfer, if the following are

both true:

The parity-error-response bit is set in the command register of the primary

interface.

The parity-error-response bit is set in the bridge control register of the

secondary interface.

PI7C8150A completes the transaction normally.

For upstream transactions, when the parity error is being passed back from the target bus

and the parity error condition was not originally detected on the initiator bus, the following

events occur:

PI7C8150A asserts S_PERR_L two cycles after the data transfer, if the following are

both true:

The parity error response bit is set in the command register of the primary

interface.

The parity error response bit is set in the bridge control register of the

secondary interface.

06-0057

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