2.4.18: aic7xxx soft reboot broken

[Matthew Derer <matthew@alumni.caltech.edu>]

I recently upgraded to a 2.4.18 kernel on a machine with an Adaptec 
2940AU SCSI controller.  Since the upgrade, soft reboots don't work; the 
machine appears to shut down normally, but during the subsequent boot 
the SCSI BIOS reports a timeout on an inquiry command and is unable to 
find any drives on the bus.  A hard power cycle is required to restore 
the card to a state in which it can find the drives.

Problem seems to be that the reboot notifier for the new aic7xxx driver 
is registered in aic7xxx_setup, which only gets called when there are 
module or kernel command-line params for aic7xxx.  Without reboot 
notification and cleanup, the card is left in a bad state at shutdown, 
and BIOS does not appear to clean it up during boot.

I think other people have run into the same problem:

http://groups.google.com/groups?selm=20010811.180158.1012502954.2309%40omit.nonsense.bigfoot.com

Workaround is obvious, just feed the module any param to get the 
notification registered, like aic7xxx=verbose, then soft reboots work 
just fine.  Fix would be to register the notifier whether there are 
params or not.  Also wouldn't hurt to check for SYS_POWER_OFF as well as 
SYS_HALT and SYS_DOWN when handling the notify, SYS_POWER_OFF can result 
in a halt without actually powering off on some machines.

Matthew