On Wed, 1 Sep 1999, Leonard N. Zubkoff wrote:
> Date: Tue, 31 Aug 1999 23:26:00 +0200 (MET DST)
> From: Gerard Roudier <[EMAIL PROTECTED]>
>
> On Mon, 30 Aug 1999, Larry Augustin wrote:
>
> > I seem to recall that on the SC450NX, the GPIO3 pin is used in
> > conjunction with the addition of a Mylex AcceleRAID that takes over
> > the on-board Symbios SCSI channels.
>
> As far as I know, the issues with the DIFF sensing have nothing to do with the
> Mylex cards.
The issue could be the following:
Do SC450NX mother boards and/or some Mylex AcceleRaid boards use the
GPIO3 pin for specific purpose ?
In order for SYM53C8XX chips to work with HVD SCSI, a bit must be set in
an IO register. So, Mylex cards that support HVD SCSI with SYM53C8XX
controllers have to know if the BUS is HVD SCSI or not, in order to
configure correctly the SYM53C8XX chips. But perhaps, they just donnot
support HVD with SYMBIOS devices, given LVD, which is a far better
replacement of HVD.
The GPIO3 was documented by SYMBIOS as the bit that should be checked to
probe differential SCSI controllers. It was so for the 825, 825A, 875, 876
and 885 PCI-SCSI chips. As I wrote in a previous mail, the 896 does report
the BUS mode through an IO register (based on the DIFFSENS signal) and so
GPIO3 is no more used by SYMBIOS on 896-based controlllers for SCSI
differential probing.
Result is that drivers for SYMBIOS PCI-SCSI chips should just not care
about GPIO3 for 896 controllers and I just applied the corresponding fix
to my current driver versions.
A problem may remain if GPIO3 is used somewhere for anything else than
SCSI differential indicator when SYM53C875/876/825A are used. For this
case, I donnot have information about Intel Motherboards, and Mylex boards
that use external SYM53C8XX SCSI chips (therefore possibly driven direclty
by sym/ncr53c8xx drivers).
If you have some infos about some specific use of GPIO3 by some hardware
you know very well, you may want to let me know.
Thanks in advance, Leonard.
Regards,
G�rard.
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