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SubjectRe: [PATCH] PM: Make system-wide PM and runtime PM treat subsystems consistently
Date
On Friday, February 18, 2011, Greg KH wrote:
> On Fri, Feb 18, 2011 at 12:54:25AM +0100, R. J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > The code handling system-wide power transitions (eg. suspend-to-RAM)
> > can in theory execute callbacks provided by the device's bus type,
> > device type and class in each phase of the power transition. In
> > turn, the runtime PM core code only calls one of those callbacks at
> > a time, preferring bus type callbacks to device type or class
> > callbacks and device type callbacks to class callbacks.
> >
> > It seems reasonable to make them both behave in the same way in that
> > respect. Moreover, even though a device may belong to two subsystems
> > (eg. bus type and device class) simultaneously, in practice power
> > management callbacks for system-wide power transitions are always
> > provided by only one of them (ie. if the bus type callbacks are
> > defined, the device class ones are not and vice versa). Thus it is
> > possible to modify the code handling system-wide power transitions
> > so that it follows the core runtime PM code (ie. treats the
> > subsystem callbacks as mutually exclusive).
> >
> > On the other hand, the core runtime PM code will choose to execute,
> > for example, a runtime suspend callback provided by the device type
> > even if the bus type's struct dev_pm_ops object exists, but the
> > runtime_suspend pointer in it happens to be NULL. This is confusing,
> > because it may lead to the execution of callbacks from different
> > subsystems during different operations (eg. the bus type suspend
> > callback may be executed during runtime suspend of the device, while
> > the device type callback will be executed during system suspend).
> >
> > Make all of the power management code treat subsystem callbacks in
> > a consistent way, such that:
> > (1) If the device's type is defined (eg. dev->type is not NULL)
> > and its pm pointer is not NULL, the callbacks from dev->type->pm
> > will be used.
> > (2) If dev->type is NULL or dev->type->pm is NULL, but the device's
> > class is defined (eg. dev->class is not NULL) and its pm pointer
> > is not NULL, the callbacks from dev->class->pm will be used.
> > (3) If dev->type is NULL or dev->type->pm is NULL and dev->class is
> > NULL or dev->class->pm is NULL, the callbacks from dev->bus->pm
> > will be used provided that both dev->bus and dev->bus->pm are
> > not NULL.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > Acked-by: Kevin Hilman <khilman@ti.com>
> > Reasoning-sounds-sane-to: Grant Likely <grant.likely@secretlab.ca>
>
> Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
>
> You are going to take this through your tree, right?

Yes, I am. Thanks!

Rafael


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