is there a way to force the aic7xxx driver to use a SLOWER speedthan it detects?

[Todd Denniston]

is there a way to force the aic7xxx driver to use a SLOWER speed than it
detects?

I would like to force it to use one or two steps down in the scsi speed
settings
80.000MHz (w/o DT)
40MHz
20MHz

can this be done at the driver level?
would I have to mod the code, or is there an option I have not understood?

Adaptec AIC7xxx driver version: 6.3.5
Adaptec 3960D Ultra160 SCSI adapter
aic7899: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs
Allocated SCBs: 20, SG List Length: 102

Target 0 Negotiation Settings
        User: 160.000MB/s transfers (80.000MHz DT, offset 127, 16bit)
        Goal: 160.000MB/s transfers (80.000MHz DT, offset 62, 16bit)
        Curr: 160.000MB/s transfers (80.000MHz DT, offset 62, 16bit)
        Channel A Target 0 Lun 0 Settings
                Commands Queued 1368727
                Commands Active 16
                Command Openings 0
                Max Tagged Openings 16
                Device Queue Frozen Count 0

It's a RM8000 and does not do the DV dance with the aic7xxx driver, so Promise
suggested slowing down the bus and I haven't yet found a way.

-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane) 
Harnessing the Power of Technology for the Warfighter