82375EB datasheet(91/131 Pages) INTEL

91 / 131 page

82375EBSB

As a master the PCEB does not know if it is accessing the same target and thus does not generate fast

back-to-back accesses As a slave the PCEB is capable of decoding fast back-to-back cycles

290477 – 65

Figure 23 Arbitration for Back-to-Back Access

543 RETRY THRASHING RESOLVE

When a PCI initiator’s access is retried the initiator releases the PCI Bus for a minimum of two PCI clocks and

then normally requests the PCI Bus again To avoid thrashing of the bus with retry after retry the PCI arbiter’s

state tracer provides REQ

masking Tracking retried masters requires latching GNT

during FRAME

that the correct retried master can be masked The state tracer masks a REQ

after that particular agent is

retried on the PCI Bus The state tracer differentiates between two retry events The two events include PCEB

target retries and all other retries

For initiators that were retried by the PCEB as a target the masked REQ

is flagged to be cleared upon

RESUME

active All other retries trigger the Master Retry Timer (described in Section 5442 Master Retry

Timer) When this timer expires the mask is cleared

5431 Resume Function

The PCEB forces a retry to a PCI master (resulting in masking the REQ

of that master) for the following

1 Buffer management activities (See Section 60 Data Buffering)

2 The EISA Bus is occupied by an EISAISA master or DMA

4 The PCEB is locked as a resource and PLOCK

is asserted during the address phase

82375EB Datasheet(PDF) 91 Page - Intel Corporation