[Linux-parport] ECP question

Adam Baker parport at baker-net.org.uk
Mon Oct 11 19:18:36 EDT 2004

On Monday 11 October 2004 18:58, Joe Henley wrote:
> Hi,
> On my Intel 875PBZ mobo, running Red Hat 9 (kernel 2.2.20-20.9), I have
> the BIOS set to ECP for the parallel port.  But the info in the
> /var/log/messages file says it's only supporting PCSPP and TRISTATE.
> I need to use ECP for a parallel port scanner.  Can anyone offer any
> suggestions?
Are you sure it is ECP you need - it is EPP that is critical for my parallel 
port scanner and I believe that is the case for all ones that use the ppscsi 

In either case you should try turning on the verbose_probing option. That will 
log a lot more of what is being tested and where it is failing. I don't know 
what SuperIO chip that board uses but there is a problem with detecting EPP 
on the ITE IT8703F-A, you need to comment out the block of code shown below.

        /* Check for Intel bug. */
        if (priv->ecr) {
                unsigned char i;
                for (i = 0x00; i < 0x80; i += 0x20) {
                        ECR_WRITE (pb, i);
                        if (clear_epp_timeout (pb)) {
                                /* Phony EPP in ECP. */
                                return 0;

For some reason I find that modprobe parport_pc verbose_probing=1 irq=auto 
correctly detects ECP mode but modprobe parport_pc verbose_probing=1 irq=7 
fails even though the former correctly identifies the assigned IRQ as 7

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