Over Christmas break I decided to configure my laptop (running Gentoo Linux) to print to my parent's new Oki Data C5400 (they actually have a C5400n, the same model but with a networking printing card). At the time of this page's creation, there is basically no information about this printer's Linux / CUPS compatibility. Oki claims in several places that it works, but I've yet to see a page yet that confirms this (such as linuxprinting.org).
Printer Specs:I first used IPP to try to print. The URI location was: ipp://hostname/ipp. This worked perfectly. Later I tried printing via USB which also worked fine.
I didn't see a PPD readily available for the printer, so I configured it as an HP LaserJet 4 and it printed fine in black and white. To get color printing to work I copied the PPD file off our MacOS X box and it worked like a charm. The print quality was just as good as on the Mac (which is what you would expect since they both use CUPS). It appears that the MacOS X installer installs a generic Postscript driver. You might find it useful, so here it is: OkiC5400.ppd. I don't know if it's redistributable, so I hope I don't get in trouble.
After searching around for a while I found a PPD that Oki offers for this model:
It's GPL'ed so here is a mirror in case Oki's removes it from their site: ok5400u1.ppd
After installing the PPD file (see www.linuxprinting.org for installation details) I did several test prints. Everything seemed to print very well. This PPD file does seem to have issues though such as having "{printer_make_and_model}" in the title bar and the "Configure Printer" page (the CUPS web interface) fails with: "Error: server-error-device-error". I'll try to fix these soon.