Re: [Bug 197863] Thinkpad X240 resume dramatically slower on kernels 4.13+

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Hi Oliver,

On Tue, Jan 30, 2018 at 08:45:17AM +0100, Oliver Neukum wrote:
> Am Montag, den 29.01.2018, 19:21 +0100 schrieb Markus Demleitner:
> > 
> > Any guess what might be behind this?
> > 
> have you checked the persist attribute between the versions working
> well and working badly?

Persist is 1 in both cases.  But persist was a good point anyway --
there's *probably* little point having an LTE card persist (I don't
think it could keep registered with the mobile network on 5..25 mW),
and so I tried 

echo 0 > /sys/bus/usb/devices/1-4/power/persist

before suspending.  Doing this three times before a suspend, the box
came back three out of three with 4.15.0.  Suspending without the
intervening write immediately brought back the 10 s timeout.  Then
again two fast resumes with an echo before it.  And another one.

So -- I think I have a good workaround for me[1].

I'll try to get myself to git-bisecting the problem, because I see
it'd be better if we could figure out why persist hasn't been a
problem before 4.13.0 and has been causing the long resume delay from
then on.  I'm not making actual promises, though (I'm a bit scared of
checkout sizes, build times, and lots of reboots; log(n) still rises
fairly steeply for low n...)

Thanks for providing the useful hint,

         Markus


[1] For anyone who ended up here looking for a solution:  I dumped

  #!/bin/sh
  case "$1" in
	  suspend|hibernate)
		  echo 0 > /sys/bus/usb/devices/1-4/power/persist
		  ;;
  esac
  exit 0

into a file

/etc/pm/sleep.d/05sierra

(works with pm-utils, probably not with systemd)

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