I'm still wondering why this function in parport_pc.c rejects dma
values of zero.  Is DMA0 not usable by the parallel port for some
reason?  I should think that if the PnP BIOS returns a dma of zero
then it means that the parallel port is using DMA0.  Sorry if I'm
being obtuse.                      // Thomas Hood 

parport_pc.c line 2799:
int init_pnp040x(struct pci_dev *dev)
{       int io,iohi,irq,dma;

        io=dev->resource[0].start;
        iohi=dev->resource[1].start;
        irq=dev->irq_resource[0].start;
        dma=dev->dma_resource[0].start;

        if(dma==0) dma=-1;             <--- Why?

        printk(KERN_INFO "PnPBIOS: Parport found %s %s at io=%04x,%04x irq=%d dma=%d\n",
                dev->name,dev->slot_name,io,iohi,irq,dma);
        if (parport_pc_probe_port(io,iohi,irq,dma,NULL))
                return 1;
        return 0;
}