TODO:
- checkpatch.pl fixes
- fix device drivers that are broken ("depends on BROKEN" in Kconfig)
- tidy-up comments:
  - there are some "//comments" and "// comments" scattered around
  - sometimes they are misaligned
  - sometimes "// comments" are interleaved with "/* comments */"
  - multiline comments should start with initial almost-blank line:
    /*
     * Good
     * multiline
     * comment
     */
    /* Bad
     * multiline
     * comment
     */
- resolve XXX notes where possible
- fix FIXME notes
- clean-up commented-out code
- fix typos