Re: S3 resume regression [1cf4f629d9d2 ("cpu/hotplug: Move online calls to hotplugged cpu")]

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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On Wed, May 11, 2016 at 04:34:06PM +0300, Ville Syrjälä wrote:
> On Wed, May 11, 2016 at 08:44:45AM -0400, Steven Rostedt wrote:
> > On Wed, 11 May 2016 15:21:16 +0300
> > Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > 
> > > Yeah can't get anything from the machine at that point. netconsole
> > > didn't help either, and no serial on this machine. And IIRC I've
> > > tried ramoops on this thing in the past but unfortunately the memory
> > > got cleared on reboot.
> > > 
> > 
> > Can you look at the documentation in the kernel code at
> > 
> > Documentation/power/basic-pm-debugging.txt And follow the procedures
> > for testing suspend to RAM (although it requires mostly running the
> > same tests as for hibernation suspending).
> > 
> > You can also use the tool s2ram for this as well.
> > 
> > See Documentation/power/s2ram.txt
> > 
> > Perhaps this can give us a bit more light onto the problem.
> > 
> > Basically the above does partial suspend and resume, and can pinpoint
> > problem areas down to a more select location.
> 
> All the pm_test modes work fine. The only difference between them was
> that 'platform' required me to manually wake up the machine (hitting a
> key was sufficient), whereas the others woke up without help.
> 
> pm_trace gave me
> [    1.306633]   Magic number: 0:185:178
> [    1.322880]   hash matches ../drivers/base/power/main.c:1070
> [    1.339270] acpi device:0e: hash matches
> [    1.355414]  platform: hash matches
> 
> which is the TRACE_SUSPEND in __device_suspend_noirq(), so no help
> there.
> 
> I guess I could try to sprinkle more TRACE_RESUMEs around into some
> early resume code. If anyone has good ideas where to put them it
> might speed things up a bit.

So I did a bunch of that and found that it gets stuck somewhere
around executing the _WAK method:
platform_resume_noirq
 acpi_pm_finish
  acpi_leave_sleep_state
   acpi_hw_sleep_dispatch
    acpi_hw_legacy_wake
     acpi_hw_execute_sleep_method
      acpi_evaluate_object
       acpi_ns_evaluate
        acpi_ps_execute_method
         acpi_ps_parse_aml

It also seesm that adding a few TRACE_RESUME()s or an msleep() right
after enable_nonboot_cpus() can avoid the hang, sometimes.

I've attached the DSDT in case anyone is interested in looking at it.

-- 
Ville Syrjälä
Intel OTC

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