Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend

From	Alan Stern <stern@rowland.harvard.edu>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend
Date	2015-09-28 22:30 +0200
Message-ID	<qdNdE-1FC-17@gated-at.bofh.it> (permalink)
References	<qdMUj-1fb-35@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, 28 Sep 2015, Rafael J. Wysocki wrote:

> Hi Alan,
> 
> On Mon, Sep 28, 2015 at 4:29 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Mon, 28 Sep 2015, Rafael J. Wysocki wrote:
> >
> >> > This suggests we forget about power/wakeup == "off" and introduce an
> >> > "inhibit" attribute instead.
> >>
> >> If we do that, can it still be regarded as a PM attribute?
> >
> > Why not?  Consider this: Is there any reason to support inhibit when
> > CONFIG_PM is disabled?  I can't come up with any.
> 
> Well, the "I don't want any input from you now, because the phone is
> going into a pocket" case?

But who would make a phone without CONFIG_PM?  If you're sufficiently 
unconcerned about power usage that you turn off CONFIG_PM, then you 
probably don't care about getting excess input events either.

> It isn't stticlty dependent on PM.

No, not strictly.  But it is closely enough related that people
shouldn't mind if it becomes part of the PM code.

> >> > Well, I suppose there might be a driver that supports inhibit but
> >> > doesn't support runtime PM, unlikely as that seems.  Or the driver
> >> > might support both but the user might leave power/control == "on" while
> >> > inhibiting the device.
> >>
> >> That sounds like a general rather than PM-related mechanism then.
> >
> > I don't follow your reasoning.
> 
> Support for "inhibit" and lack of runtime PM support means that the
> feature has nothing to do with PM any more AFAICS.

My example above referred to support in a single driver, not support in 
the system as a whole.  By the same reasoning, since some drivers 
support system sleep but not runtime PM, system sleep must have nothing 
to do with PM.  :-)

> That's why I think it may be regarded by more than just PM.  It should
> make runtime PM behave in a specific way if supported, but then it
> should work withot it too, shouldn't it?

If you want inhibit to be part of the device core rather than the PM
core, that's okay with me.

> My opinion is that "inhibit" should affect PM, but should not require
> PM to function (there's no technical reason for that).

All right.  Then a design should be straightforward.

Alan Stern

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Thread

Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Oliver Neukum <oneukum@suse.com> - 2015-09-22 14:10 +0200
  Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-22 16:20 +0200
    Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Oliver Neukum <oneukum@suse.de> - 2015-09-22 16:40 +0200
      Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-22 17:30 +0200
        Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Oliver Neukum <oneukum@suse.de> - 2015-09-23 05:10 +0200
          Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Octavian Purdila <octavian.purdila@intel.com> - 2015-09-23 09:30 +0200
          Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-23 17:00 +0200
            Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-25 02:20 +0200
              Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-25 16:40 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-25 21:50 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-25 23:20 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-25 23:30 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-26 00:40 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-26 17:30 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-27 15:20 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-27 16:30 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-28 15:20 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-28 16:30 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend "Rafael J. Wysocki" <rafael@kernel.org> - 2015-09-28 22:10 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Alan Stern <stern@rowland.harvard.edu> - 2015-09-28 22:30 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Pavel Machek <pavel@ucw.cz> - 2015-10-04 17:20 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing  runtime suspend Pavel Machek <pavel@ucw.cz> - 2015-09-27 19:10 +0200
                Re: [RFC PATCH] PM / Runtime: runtime: Add sysfs option for forcing runtime suspend "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-28 15:20 +0200

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