ata explicit idle/standby

Hi,

I've done a small patch to the -CURRENT atacontrol and ata driver to
allow explicit switch of drives to idle or standby mode and query the
current mode. I use it to spin down disks needed only very inregularly.
If extended by a means to set the idle timeout this might be
particularly useful to notebook users as well.

Or have I actually missed the some already present functionality to
achieve the same?
-- 
Cheers,
Micha