PCI Deadlock Situations

Example: The PCI host sets the DMA buffer descriptors into the local memory, and then it runs the DMA (a write into a PowerSpan register). The DMA starts before the effective completion of the buffer descriptors writes into the local 60x memory, so it loads a bad addresses, a bad byte count, etc., and accomplishes the transfer with this bad data.

In this case, the PCI host must ensure that its latest write into the memory is effectively finished locally, before starting the DMA.

PCI Deadlock Situations

Several deadlock situations can occur on the PCI bus. These situations will statistically rarely occur, but they need to be treated by exception handlers, in order not to lock the system.

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Interphase Corporation