Re: [PATCH] driver core: Ensure proper suspend/resume ordering

From	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] driver core: Ensure proper suspend/resume ordering
Date	2015-09-17 01:40 +0200
Message-ID	<q9usW-2um-17@gated-at.bofh.it> (permalink)
References	<q9qz1-5ll-35@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wednesday, September 16, 2015 03:27:55 PM Alan Stern wrote:
> On Wed, 16 Sep 2015, Grygorii Strashko wrote:
> 
> > I think, It should prohibited to probe devices during suspend/hibernation.
> > And solution introduced in this patch might help to fix it -
> > in general, we could do :
> > - add sync point on suspend enter: wait_for_device_probe() and
> > - prohibit probing: move all devices which will request probing into
> > deferred_probe list
> > - one suspend exit: allow probing and do driver_deferred_probe_trigger
> 
> That could work; it's a good idea.
> 
> > I'd like to mention here that this patch will work only
> > if dmp_list will be filled according device creation order ("parent<-child" dependencies)
> > *AND* according device's probing order ("supplier<-consumer").
> > So, if there is the case when Parent device can be probed AFTER its children
> > - it will not work, because "parent<-child" dependencies will not be tracked
> > any more :( Sry, I could not even imagine that such crazy case exist :'(
> 
> If we avoid moving devices to the end of the dpm_list when they already 
> have children, then we should be okay, right?
> 
> > Are there any other subsystems with the same behavior like PCI?
> 
> I don't know.
> 
> > If not - probably, it could be fixed in PCI subsystem using device_pm_move_after() or 
> > device_move() in PCIe ports probe.
> > if yes - ... maybe we can scan/re-check and reorder dpm_list on suspend enter and
> > restore ("parent<-child" dependencies).
> 
> > Truth is that smth. need to be done 100%. Personally, I was hit by this issue also,
> >  and it cost me 3 hours of debugging and I came up with the same patch as
> > Bill Huang, then spent some time trying to understand what is wrong with PCI
> > - finally, I've just changed the order of my devices in DT :)
> > 
> > Also, I think, it will be good to have this patch in -next to collect more feedbacks.
> 
> I like the idea of forcing all probes during a sleep transition to be 
> deferred.  We could carry them out just before unfreezing the user 
> threads.  That combined with the change mentioned above ought to be 
> worth testing.

Agreed.

Thanks,
Rafael

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Thread

[PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-10 12:20 +0200
  Re: [PATCH] driver core: Ensure proper suspend/resume ordering Grygorii Strashko <grygorii.strashko@ti.com> - 2015-09-10 13:00 +0200
  Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-10 23:50 +0200
    Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-11 14:10 +0200
      Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-11 21:10 +0200
        Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-12 00:10 +0200
          Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-12 19:50 +0200
            Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-15 02:50 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-15 16:30 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-16 02:40 +0200
          Re: [PATCH] driver core: Ensure proper suspend/resume ordering Grygorii Strashko <grygorii.strashko@ti.com> - 2015-09-16 15:50 +0200
            Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-16 21:30 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-17 01:40 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Grygorii Strashko <grygorii.strashko@ti.com> - 2015-09-17 17:50 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-18 02:00 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-18 02:10 +0200
        Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-15 18:20 +0200
          Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-15 21:20 +0200
            Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-16 03:10 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering Grygorii Strashko <grygorii.strashko@ti.com> - 2015-09-16 15:40 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-16 19:00 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-16 19:10 +0200
            Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-16 15:20 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-16 21:30 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-17 02:00 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-17 04:10 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-17 19:10 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-17 20:50 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-17 23:10 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-18 02:20 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-18 18:00 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-19 01:10 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-21 11:00 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-21 16:40 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-22 02:00 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-22 03:30 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-22 02:40 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-17 07:50 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-17 20:20 +0200
                Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-17 21:30 +0200
      Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-12 00:20 +0200
        Re: [PATCH] driver core: Ensure proper suspend/resume ordering Thierry Reding <thierry.reding@gmail.com> - 2015-09-15 18:00 +0200
          Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-16 03:00 +0200
            Re: [PATCH] driver core: Ensure proper suspend/resume ordering Grygorii Strashko <grygorii.strashko@ti.com> - 2015-09-16 15:40 +0200
              Re: [PATCH] driver core: Ensure proper suspend/resume ordering "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-17 02:30 +0200
    Re: [PATCH] driver core: Ensure proper suspend/resume ordering Alan Stern <stern@rowland.harvard.edu> - 2015-09-11 16:10 +0200

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