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@xxxxxxx> > > > > 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@xxxxxxx> > > Acked-by: Kevin Hilman <khilman@xxxxxx> > > Reasoning-sounds-sane-to: Grant Likely <grant.likely@xxxxxxxxxxxx> > > Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxx> > > You are going to take this through your tree, right? Yes, I am. Thanks! Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
