On Tue, Feb 15, 2011 at 10:10:06AM -0800, Kevin Hilman wrote: > "Rafael J. Wysocki" <rjw@xxxxxxx> writes: > > > 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, while the device > > type callback will be executed during runtime resume). > > > > Make all of the power management code treat subsystem callbacks in > > a consistent way, such that: > > (1) If the device's bus type is defined (eg. dev->bus is not NULL) > > and its pm pointer is not NULL, the callbacks from dev->bus->pm > > will be used. > > (2) If dev->bus is NULL or dev->bus->pm is NULL, but the device's > > device 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. > > (3) If dev->bus is NULL or dev->bus->pm is NULL and dev->type is > > NULL or dev->type->pm is NULL, the callbacks from dev->class->pm > > will be used provided that both dev->class and dev->class->pm > > are not NULL. > > > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> > > This looks good, consistency between system and runtime PM is a great > help to readability. > > Acked-by: Kevin Hilman <khilman@xxxxxx> Reasoning-sounds-sane-to: Grant Likely <grant.likely@xxxxxxxxxxxx> _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
