Hi,
I think your supposed to ensure that the generic SCSI driver
supports simpler commands like TEST UNIT READY and INQUIRY, etc,
before using READ or WRITE.
Let me know if this helps.
Balbir Singh
On Mon, 30 Nov 1998, Walter Heath (group 42) wrote:
>
> Hi,
>
> We are working on a project for the FAA that will provide local
> weather products for air traffic controllers using local radar
> returns as a source data. We would like to embed an AMPRO Little Board
> /P5e PC board in the radar receiver so that we can control/monitor the
> receiver via Ethernet. One interface to the receiver is through a
> SCSI port. We would therefore like to use the Linux generic SCSI
> driver to talk to the receiver.
>
> The Little Board uses the Adaptec aic-7680Q SCSI interface chip.
>
> I have been using the "handle_SCSI_cmd()" function described in the
> Linux LDP SCSI-Programming-HOWTO document to establish an interface
> to the receiver SCSI port.
>
> The INQUIRY command, described in the document works OK. I get the
> response expected from the receiver. However, I seem to be unable
> to send any data to the device. For example, a SCSI WRITE (0x0a)
> command does not work. The generic driver does not deliver any error
> message when the command fails.
>
> The receiver SCSI port works OK with standard workstations (e.g.,
> DEC, HP, SGI), so that end is OK.
>
> I have also tried a similar test with an Exabyte tape drive. In this
> test my program sends a MODE SELECT command that sets the read retry
> count to 5 and the write retry count to 8. Then it does a MODE SENSE
> command that reads back 7 and 11, respectively, for the two retry
> counts. I suspect these are the defaults and the MODE SELECT command
> did not work. This is the same symptom I saw with the receiver --
> writes to the SCSI device don't work (the INQUIRY also works for the
> tape drive). Again, the driver does not report any errors.
>
> I was wondering if you have heard of any problems with the aic-7860Q
> device. In one of the SCSI-FAQ documents a comment was made that some
> of the "new" (date unspecified) Adaptec chips have problems.
>
> Our SCSI cable is reasonably short. There is a ribbon cable coming
> off the board. I made that part short (less than one inch) and rung
> out the entire cable.
>
> We will be trying another Little Board, to see if there might be
> something wrong with the aic-7860Q chip on this board.
>
> I also printed the aic7xxx.c file that was part of our Slackware 3.5
> distribution (Linux 2.0.34). Its rather large (132 pages!). I will
> start looking at it soon. I would appreciate any advice on which parts
> of it I should look at for this problem. That would save me some time.
>
> I am also wondering if processor speed could be a problem. I believe
> the Little Board we have is running a 133 MHz Pentium.
>
> I will also try to find a SCSI protocol analyzer.
>
> Any suggestions you have will be greatly appreciated. As you can see,
> this interface is key to our design, so we will need to spend the
> time required to fix this problem.
>
> Thanks in advance for your help!
>
>
>
>
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