[1252] in linux-scsi channel archive
Sync speed negotiation
daemon@ATHENA.MIT.EDU (Kenneth Albanowski)
Fri Jan 10 07:42:39 1997
Date: Fri, 10 Jan 1997 07:23:58 -0500 (EST)
From: Kenneth Albanowski <kjahds@kjahds.com>
To: linux-scsi@vger.rutgers.edu
I've just subjected myself to purchasing and installing an Adaptec 2940AU,
and am now seriously berating myself for doing so.
That aside, there was one issue that the Linux kernel could have been more
helpful with: currently the sync negotiation in the aic7xxx driver (and
perhaps others, I haven't checked) chooses the highest speed that the SCSI
device and the controller can agree on. Unfortunately, my system was
completely unable to boot at the 10Mhz it locked into. Only with some
major juggling was I able to compile a kernel that only did 3.6Mhz
negotation, and could thus boot.
I'd like to suggest that there should be some way of defaulting to the
slowest speed, or, perhaps better, on a SCSI timeout error, reduce the
maximum negotation speed for that ID. As far as I can tell, the aic7xxx
driver can't make use of the Adaptec BIOS settings, so they aren't much
use in telling the thing to slow itself down.
At the very least, boot disks for distributions really ought to use the
slowest speed, not the highest.
If I've missed something important, please feel free to inform me.
--
Kenneth Albanowski (kjahds@kjahds.com, CIS: 70705,126)
