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PI7C7100
3-Port PCI Bridge
ADVANCE INFORMATION
7.4 System Error (SERR#) Reporting
PI7C7100 uses the P_SERR# signal to report conditionally a number of system error conditions in addition to the special
case parity error conditions described in Section 7.2.3.
Whenever assertion of P_SERR# is discussed in this document, it is assumed that the following conditions apply:
• For PI7C7100 to assert P_SERR# for any reason, the SERR# enable bit must be set in the command register.
• Whenever PI7C7100 asserts P_SERR#, PI7C7100 must also set the signaled system error bit in the status register.
In compliance with the PCI-to-PCI Bridge Architecture Specification, PI7C7100 asserts P_SERR# when it detects the
secondary SERR# input, S_SERR#, asserted and the SERR# forward enable bit is set in the bridge control register. In
addition, PI7C7100 also sets the received system error bit in the secondary status register.
PI7C7100 also conditionally asserts P_SERR# for any of the following reasons:
• Target abort detected during posted write transaction
• Master abort detected during posted write transaction
• Posted write data discarded after 2
24
(default) attempts to deliver (2
24
target retries received)
• Parity error reported on target bus during posted write transaction (see previous section)
• Delayed write data discarded after 2
24
(default) attempts to deliver (2
24
target retries received)
• Delayed read data cannot be transferred from target after 2
24
(default) attempts (2
24
target retries received)
• Master timeout on delayed transaction
The device-specific P_SERR# status register reports the reason for the assertion of P_SERR#.
Most of these events have additional device-specific disable bits in the P_SERR# event disable register that make it
possible to mask out P_SERR# assertion for specific events. The master timeout condition has a SERR# enable bit for
that event in the bridge control register and therefore does not have a device-specific disable bit.