timeout with pata dvd-drive

hi everybody,

i'm experiencing this issue for quite some time now. i already filed a PR
about it and wrote several mails to various mailinglists without success. :(

the problem is that my pata-dvddrive takes forever to access a cdr, because i
get a lot of timeouts. booting with a cdr inserted takes > 5 minutes.

you can find the PR here: http://www.freebsd.org/cgi/query-pr.cgi?pr=133122

i've attached a verbose dmesg. the problem seems to start in line 1389. right
now i'm running r191768M.

cheers.
alex