Re: [PARPORT] Linux and Parallel port Orb drives
Fri, 2 Jul 1999 07:51:11 -0400 (EDT)

> I am trying to get my 486 linux box (with a SPP) to recognise my orb drive.

Be warned that the performance will be dreadful on that old port.

> parport0: PC-style at 0x378 [SPP]
> paride: version 1.04 installed
> paride: on26 registered as protocol 0
> pd: pd version 1.05, major 45, cluster 64, nice 0
> pda: 0x378 is parport0
> pda: on26: port 0x378, mode 0, test=(130,149)
> pda: on26: port 0x378, mode 1, test=(255,255)
> pda: Autoprobe failed
> pd: no valid drive found
> What does this mean?

The critical information is: test=(130,149)

The driver does some data integrity tests - it writes a sequence of numbers
to the registers in the actual disk drive and reads them back. If the
numbers read back don't match what was written, an error is noted.

It does this in two batches, one directed to the master drive and one to
the slave. Depending on the device, one or the other is expected to fail.
Some drives respond to this test as both the slave and the master. The
ORB is in the latter category, but the results tell us that the data
path between your CPU and the disk is very flaky: on the first pass,
130 of the 256 tests failed, on the second pass 149 failed.

You could try to adjust the "port delay" parameter to see if that helps.
Read the comments at the start of pd.c for details. The units are
microseconds and the default is 1. Increasing the number beyond 6 is
probably pointless. I've seen a few parallel ports that needed a setting
of 4 (typically on old VLB multi-I/O cards). If yours is in that
category, do not expect to see better than 30Kb/s transfer rates !
(The old ports often had excessive capacitance, which prevents signals from
stabilising quickly.)

> Also is there a way to do all of this automatically when mounting the drive
> (ie using conf.modules). Currently when I try to do mount /mnt/orb I get the
> following message
> mount: the kernel does not recognize /dev/pda5 as a block device
> (maybe `insmod driver'?)

Well, until you get the module to load, it won't be there :-)

There are ways to get conf.modules to do the job, or you can insmod the
drivers manually in rc.local ...

This has been discussed several times before on the mailing list. Give
the (new) search engine on the parport homepage a try.

Grant R. Guenther

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