machine/ncr5385.cpp: delay after XFI_OUT_ACK #13302
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Elektraglide
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OK, found the smoking gun in the tek4404 bootrom. It does not expect the signal to arrive so quickly so clears the variable tracking IRQ_SCSI_complete and then waits for it to be set. which it now never will be. The delay means it has time to clear IRQ_SCSI_complete and then go into its busy wait loop.
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Without a delay after state XFI_OUT_ACK, tek4404 cannot load anything.
Trial and error determined a delay of <3.5us does not work, more than 3.5us does work.
I dont understand exactly why, but tek4404 scsi code just never sees the state change without this.
[I appreciate code changes and not understanding root-cause are not great, but this does resolve all issues with scsi for tek4404.]