Comment 42 for bug 952556

A related issue here, I have a Samsung HS122JC in my Dell D430, and after updating to XUbuntu 12.04, I noticed that the HD started surging on battery power. Basically it spins up a bit faster for a while and the drive LED on the laptop glows solid for a moment while everything hangs, then it frees itself and resumes operation.

I messed around a bit, then noticed in the PM logs that you're setting the APM_Level to 127 on battery, but my HD only knows of 1, 128 and 254. Depending on what you set using hdparm -B, the drive rounds it down to the lower number. Setting it to 127 rounds the APM_Level to 1 and the drive starts doing these interesting things. Looking in the hdparm package's change log (and my pm-powersave.log), it seems you guys used 128 up until 11.10, and that's why it happened to work with my drive.

I set apm_battery = 128 in /etc/hdparm.conf and am happy again. I wonder what APM_Level = 1 really means to this drive.. Doesn't seem like a power saving mode in any case, more like a super high performance mode that somehow doesn't quite work (due to the hangs).

The drive itself reports what the level ended up being, so perhaps you guys might want to "fix" this by testing it in the package's install script. If the drive won't go to 127, then see if 128 still works and preconfigure /etc/hdparm.conf?

Here's some log snippets.

AC -> Battery
--
Running hook /usr/lib/pm-utils/power.d/95hdparm-apm true:

/dev/sda:
 setting Advanced Power Management level to 0x7f (127)
 APM_level = 1

/usr/lib/pm-utils/power.d/95hdparm-apm true: success.
--
Battery -> AC
--
Running hook /usr/lib/pm-utils/power.d/95hdparm-apm false:

/dev/sda:
 setting Advanced Power Management level to 0xfe (254)
 APM_level = 254

/usr/lib/pm-utils/power.d/95hdparm-apm false: success.
--