ZHCSS38 july 2020 TSB82AF15-EP
PRODUCTION DATA
The bridge converts interrupts from the PCI bus sideband interrupt signals to PCIe interrupt messages. Since the 1394a OHCI only generates INTA interrupts, only PCIe INTA messages are generated by the bridge.
PCIe Assert_INTA messages are generated when the 1394a OHCI signals an INTA interrupt. The requester ID portion of the Assert_INTA message uses the value stored in the primary bus number register (see Section 10.6.1.12) as the bus number, 0 as the device number, and 0 as the function number. The tag field for each Assert_INTA message is 00h.
PCIe Deassert_INTA messages are generated when the 1394a OHCI deasserts the INTA interrupt. The requester ID portion of the Deassert_INTA message uses the value stored in the primary bus number register as the bus number, 0 as the device number, and 0 as the function number. The Tag field for each Deassert_INTA message is 00h.
Figure 10-4 and Figure 10-5 show the format for both the assert and deassert INTA messages.
Figure 10-4 PCIe Assert_INTA Message
Figure 10-5 PCIe Deassert_INTX Message