[ltp] Hibernate/suspend for a T420

[David Woodfall]

>Linux raven 4.4.88 #2 SMP Thu Sep 14 14:21:06 CDT 2017 x86_64 Intel(R)
>Core(TM) i5-2520M CPU @ 2.50GHz GenuineIntel GNU/Linux
>
>I have suspend and hibernation support.
>
>I few days ago I decided to see if my old hibernate/suspend scripts
>work.
>
>They basically do a:
>
>sync
>echo -n shutdown > /sys/power/disk
>echo -n disk > /sys/power/state
>
>and
>
>sync
>echo -n shutdown > /sys/power/disk # although I used to not use this.
>echo -n mem > /sys/power/state
>
>They didn't work as expected so looking around I found that the thing
>to try would be to stop the extra cores, and just leave one running
>for sleeping/waking. So I added:
>
>for i in /sys/devices/system/cpu/cpu*/online ; do
>   echo 0 >$i
>done
>
>before, and:
>
>for i in /sys/devices/system/cpu/cpu*/online ; do
>   echo 1 >$i
>done
>
>after.
>
>This worked well. I could suspend, and then if I open the laptop lid
>an inch or two, it would wakeup. I didn't really try out hibernate
>mode.
>
>Anyway, now I cannot suspend or hibernate at all. The laptop doesn't
>fully turn off. It seems to shut down, but the power button is still
>lit up and the fan seems to still be running. Nor does it beep when I
>enter suspend, like it did. I haven't cheanged any system settings.
>
>So, I tried pm-suspend and pm-hibernate to see if they would work, and
>the same thing happens.
>
>Any ideas?

Well, I found the culprit: pulseaudio. If I stop it and restart it on
resume/wake, everything works fine.