Re: Followup on 274xT Adaptec

Doug Ledford (
Tue, 09 Sep 1997 21:00:31 -0500

> Ok, per Doug's request I hacked up the driver to panic just before
> scanning Chan. A. Here's what transpires:

Thanks :)

> aic7xxx: <Adaptec AHA-274X SCSI host adapter> at EISA 2
> aic7xxx: BIOS enabled, IO Port 0x2c00, IRQ11 (level sensitive) Rev <= C
> aic7xxx: Extended translation disabled.
> aic7xxx: Twin Channel, A SCSI ID 7, B SCSI ID 7, 4/4 SCBs, Qfull 4, \
> QMask 0x7

This is what I wanted to see. We are setting the p->bus_type = AIC_TWIN
prior to our call to loadseq();

> aic7xxx: Downloading sequencer code... 378 Instructions downloaded

My 2842 only downloads 369 instructions, so this looks like we are getting
the twin channel sequencer support.

> scsi0: Adaptec AHA274X/284X/294X (EISA/VLB/PCI - Fast SCSI) 4.1/3.2
> scsi: 1 host
> Kernel panic <6>scsi0: Scanning Channel A for devices

Justing, according the the books on these chipsets, what exact conditions
can cause the settings of SIMODE0 and 1 to get changed, and does it matter
if we set the conditions prior to enabling the bus drivers? Could the fact
that we are doing the outb(ENABLE, p->base + BCTL); after we set the SIMODE?
registers be causing the B channel settings not to take? Also, I wonder how
a completely absent cable and termination would effect how the card handles
these things. Steve, if you go ahead and put a device on the second
channel, does it work then? I think I recall you saying there currently
isn't anything on the second channel.

* Doug Ledford                      *   Unix, Novell, Dos, Windows 3.x,     *
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