Patch-ID# 100043-01
Keywords:	sun4 panic regs accessed busy xy450 xy451
Synopsis:panic: regs accessed while busy
Date: 20-Dec-89

SunOS release:
	4.0.3

Bug ID's fixed with this patch:
	1029802

Patches which conflict with this patch:
	100041

Architectures for which this patch is available:
	sun4

Obsoleted by:
	4.1

Problem description:

	This panic occurs on high-speed Sun-4 CPU's - the controller cannot
	set flag bits in the CSR (and let them settle) before the CPU begins
	polling to see if the bits are set.  This leads to a race condition
	which causes the panic: the status bits are not in the correct state
	and the CPU will abort just before starting the next data transfer.

	The patch puts a short delay in the driver in between setting the
	bits and polling the controller status register.