waking up an ata harddrive from idle/suspend mode without timeouts

[Jochen Eisinger <jochen@penguin-breeder.org>]

Hi,

I want to spin down my (laptop) harddrive if I don't need it for some
time. I can achieve this for example using

atactl /dev/wd0c apmset 63

This works fine, the hd spins down after some time. The next time
something tries to access the hd thou I get timeouts (as predicted by
atactl(8)) which isn't really too grave, since the wd driver can recover
from this and just tries the request again.

I wonder however why the ata driver didn't remember the apm level was
set to something <= 126 and checks whether the device is suspended
before accessing it. This would mean a performance loss, but hey, apmctl
<=126 isn't meant for performance tuning, but to reduce power
consumption and noise.

Is there some way to achieve this behaviour (i.e. avoid the timeouts, or
have the ata driver wake up the drive before using it)?

kind regards
-- jochen