Re: aic7xxx Driver support faster than 20MB/sec?

Matthias Andree (mandree@sx1.HRZ.Uni-Dortmund.DE)
Fri, 4 Dec 1998 12:25:55 +0100

On Thu, Dec 03, 1998 at 04:42:25PM -0800, Timm Gleason wrote:
> Does anyone know if the current version of the aic7xxx driver(5.1.4) support
> faster than 20MB/sec maximum transfer rate? I compiled a 2.0.36 kernel using
> the pre13 patch and the patch text had references in it to the aic7xxx
> driver being 5.0.20. This kernel did support the higher rates. However, I
> find that the kernel we compiled using the final release of 2.0.36 contains
> aic7xxx driver 5.1.4 and does not seem to accept negotiation higher than
> 20MB/sec. Yes, I have checked the SCSI BIOS for the controller and all ID's
> are set to 80MB/sec rate.

You're not stating if you have U2SCSI, but I assume you don't. So I can
assume you are messing up MB/s and MXfers/s: The MB/s are derived from
MXfers/s and the actual transfer width. So, 20 MXfers/s on a narror bus are
20 MB/s, 20 MXfers/s with a 16bit wide transfer gives 40 MB/s (which is what
you can probably achieve with the 20 MHz setting), a 32 bit wide transfer
would offer 80 MB/s, but I doubt your equipment actually does 32 Bit

In any case, the NEGOTIATION is done in MXfers/s (5 is "standard", 10 is
Fast, 20 is Ultra, regardless of width, and Width is 8 for "standard", 16
and 32 are for Wide scsi, regardless of Ultra/Fast), so 20 MB/s seems very
reasonable and is nothing which could limit your SCSI performance.

Matthias Andree
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