1. Start of driver tree usage upon suggestion from Pavel Machek.
     This still will needs a lot of further work in the future, but
     the current code doesn't hurt anything and allowa Pavel to work
     further from the base line. In esp. natively implemented
      suspend to file requires this - which I would love to see comming
     in,since I'm quite frequently using a notebook myself.

2. Kill the _IDE_C macro, which was playing games on entierly
     unnecessary declarations inside of header files in esp ide_modes.h

3. Replace the functionally totally equal system_bus_block() and
     ide_system_bus_speed() functions with one simple global
     variable: system_bus_speed. This saves quite a significatn amount of
     code. Unfortunately this is the part, which is makeing this
     patch to appear bigger then it really is...

4. Use ide_devalidate_drive() directly instead of idedisk_revalidate().

5. Kill conditional CONFIG_KMOD as well as some other minor tweaks.

Well this isn't that much in terms of functionality,  but it took me
quite q bit of time to catch up on the patch-2.5.5.gz ;-)