Comment # 10 on bug 996543 from Takashi Iwai

(In reply to Bernhard Wiedemann from comment #9)
> so since it did not crash every time, I made a loop around the test
> 
> lenovo:~ # cat /sys/power/pm_test
> none core processors platform devices [freezer]
> lenovo:~ # echo mem > /sys/power/state 
> lenovo:~ # for i in 1 2 3 4 5 ; do echo mem > /sys/power/state ; sleep 5 ;
> done
> lenovo:~ # echo devices > /sys/power/pm_test
> lenovo:~ # for i in 1 2 3 4 5 6 7 8 ; do echo mem > /sys/power/state ; sleep
> 5 ; done
> lenovo:~ # echo platform > /sys/power/pm_test
> lenovo:~ # for i in 1 2 3 4 5 6 7 8 ; do echo mem > /sys/power/state ; sleep
> 5 ; done
> lenovo:~ # echo processors > /sys/power/pm_test
> lenovo:~ # for i in 1 2 3 4 5 6 7 8 ; do echo mem > /sys/power/state ; sleep
> 5 ; done
> lenovo:~ # echo core > /sys/power/pm_test
> lenovo:~ # for i in 1 2 3 4 5 6 7 8 ; do echo mem > /sys/power/state ; sleep
> 5 ; done
> 
> but now it passed all of them.
> As a side-note: each suspend caused 8 or 9 pings to be lost.
> 
> only with none it crashed (on first try even)
> 
> Could still be an esoteric HW-problem... e.g. touching the power button in a
> certain way on resume causes a voltage to be introduced somewhere it should
> not be... 
> or the time of the sleep state matters with DRAM capacitors discharging over
> time.
> 
> 
> 
> Then I also tried alternating
> echo freeze > /sys/power/state
> and
> echo disk > /sys/power/state
> 
> and found that freeze did something on some tries
> but returned device-or-resource-busy on other tries
> and suspend-to-disk worked fine three times in a row.
> None of these crashed the laptop.

Hrm, so it happens at the lower level than kernel.  Does S4 work with this
machine, or does it show also the same hang?