[Linux-parport] EPP mode on SIIG Cyberparallel PCI

[Adam Baker]

On Sunday 22 February 2004 5:07 pm, mike dillon wrote:

> I just bought a Cyberparallel PCI card from SIIG to get an EPP-capable
> parallel port on a new legacy-free motherboard. My goal is to use it to
> drive an old UMAX parallel-port scanner.
>
> The problem is that the port is not being recognized as supporting EPP.
> I am attempting to use the card under the 2.6.2-1.74 kernel from Fedora
> Core development.
>
>
> Here is the parport driver output from dmesg:
>
> PCI parallel port detected: 131f:2020, I/O at 0x8800(0x8c00)
> parport0: PC-style at 0x8800 (0x8c00) [PCSPP,TRISTATE]
> parport0: cpp_daisy: aa5500ff(38)
> parport0: assign_addrs: aa5500ff(38)
> parport0: cpp_daisy: aa5500ff(38)
> parport0: assign_addrs: aa5500ff(38)
> lp0: using parport0 (polling).
>
> Is there something I can do to get this card working in EPP mode, or
> did I just buy the wrong hardware? It is listed as supported at
> <http://people.redhat.com/twaugh/parport/cards.html>, so I assumed that
> it would be supported in EPP mode, not just SPP.
>
You could be hitting the same problem I found with an Asus motherboard and ITE 
IT8703F-A  Super IO chip. There is a test in the parport PC driver for a bug 
in an old Intel chip set that caused EPP mode to be falsely reported as 
supported - The relevant code snippet (in 2.4.x kernels)  is

        /* 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;
                        }
                }
        }

I just commented out that section (and rebuilt and installed the modules)  and 
sudenly EPP mode sprang into life. I'd be interested to here if the same 
problem affects anyone else.

Unfortunately no-one seems to remember what chipset the test was put in for.