* When we are transferring in DATA (in asc_dma_in) and the target
is an async device, there is sometimes an extra byte in the FIFO.
If so, we need to drain that byte out of the fifo, but if and only
if the target is async. See also the comments in asc_dma_in()
in the related Mach mk84 asc driver (scsi_53C94_hdw.c), which
has an identical fix but applied in more restrictive conditions
than we need, with async *disk* targets, as well as async tapes.
* Add a watchdog and timeout active SCSI requests, to eliminate any
potential for deadlock due to applying the fix above on newer
silicon versions of the 53c94 which may not have the above problem.
Should use the MI scsi per-target timeout instead, when available.
9b84ee7f35