I've just committed a mostly rewritten driver for Mitsumi CD-ROM
drives.  Some highlights:

* It uses interrupts rather than 100 Hz polling, which improves
performance significantly (10x in my testing).

* It implements most of the CDIOC* calls, correctly.

If you have a Mitsumi drive, especially a LU002S, FX001, or FX001D,
please try it and let me know if you have any problems.