On Thu, 19 Jun 2014, Rafael J. Wysocki wrote: > Well, we used to have the notion that runtime_status is not meaningful for > devices with dev->power.disable_depth greater than 0 (except for the special > case in the suspend code path where we know why it is greater than 0). I > think > it was useful. :-)
Did we really have that notion? My memory is a little cloudy, but I thought we decided that runtime_status would not be meaningful when dev->power.runtime_error was set -- not when dev->power.disable_depth was greater than 0. Am I mixed up? In any case, I think it is reasonable to regard runtime_status as meaningful when disable_depth > 0. The PM core isn't allowed to invoke the runtime callbacks at such times, that's all. This makes perfect sense for a device that doesn't support power management and hence must always be at full power. Or when a driver knows that runtime_status is out of agreement with the device's actual power state and wants to update runtime_status directly. > > So pm_runtime_resume() and pm_request_resume() would still fail, but > > pm_runtime_get() and pm_runtime_get_sync() would work? I'm not sure > > about the reason for this distinction. > > The meaning of pm_runtime_get()/pm_runtime_get_sync() is "prevent the > device from being suspended from now on and resume it if necessary" while > "runtime PM disabled and runtime_status == RPM_ACTIVE" may be interpreted > as "not necessary to resume", so it is reasonable to special case this > particular situation for these particular routines IMHO. By the same reasoning, the meaning of pm_runtime_resume() is "resume the device now if necsesary". Since "runtime PM disabled and runtime_status == RPM_ACTIVE" means "not necessary to resume", isn't it logical for pm_runtime_resume() also to succeed under that condition? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
