Nobody seems to read Linux forum so i repost here. See original problem description at:
http://linux.pegasosppc.com/index.php?mode=forum&submode=flatthread&cmode=view&f_id=1980&offset=&forum_id=1
Yesterday at work i've written a small program for Linux which allows to drive directly all parallel port pins and test it in such a way. In the evening i took it home and ran on my Pegasos. So i discovered that parallel port on Peg perfectly works but is really locked in unidirectional XT SPP mode. It even does not allow input. This is why my scanner doesn't work (it seems to be not supporting nibble-mode data transmission). Can anyone tell me if i can reconfigure the port to bring it to at least EPP mode to enable input? May be there are some OpenFirmware options like options in PC BIOS? Or can i at least write a software which does this job?

I guess for this kind of question you'll have to contact bplan directly.

You may have to force the parallel port into EPP mode etc. with a kernel option. As far as I recall, changing the parallel port mode after boot isn't possible (it requires certain things to have been done at port initialisation, and ECP requires a DMA channel which cannot be allocated on-the-fly).

You could look at the source for the Linux "ppa" driver (Parallel Zip) which uses EPP modes. It may hint as to your problem.

Neko

Linux does not currently change parallel port mode. But fortunately the driver does have almost all necessary code. It can handle VIA686a chip and read the configuration from it (to determine base address, IRQ, DMA, mode, etc). The only thind i need is to change the code so as it will write new configuration instead of reading current one. Currently i'm working on such patch for 2.6.8 kernel. I think i'll introduce new kernel argument to activate this feature so as to keep possibility to respect BIOS settings on other architectures. I hope our south bridge is compatible with 686a.
In the future this solution will migrate to MorphOS in the form of a program which sits in WBStartup and sets port mode and preferences editor for it.