Re: [PATCH] PM: Make system-wide PM and runtime PM treat subsystems consistently

[Greg KH <greg@kroah.com>]

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?

thanks,

greg k-h