On Fri, 3 Jul 2015, Tomeu Vizoso wrote: > >> Yeah, that would remove the need for messing with the runtime PM > >> enable status of descendant devices, but I wonder why Rafael went that > >> way initially. > > > > I forget the details. Probably it was just to be safe. We probably > > thought that if a device was disabled for runtime PM then its runtime > > PM status might not be accurate. But if direct_complete is set then it > > may be reasonable to assume that the runtime PM status _is_ accurate. > > Cool.
> > Rafael and I briefly discussed ignore_children while the original > > direct_complete patch was being designed. We didn't come to any > > definite conclusion and decided to forget about it for the time being. > > Maybe now would be a good time to reconsider it. > > I would prefer to have ignore_children ignore whether the children of > a device were able to do direct_complete, rather than having a > direct_complete_default flag (plus not requiring that all its > descendants have runtime PM enabled). Okay, but remember that sometimes these "virtual" devices will exist beneath a device that needs to have ignore_children off. So this won't be a complete solution to your problem. Let's see what Rafael thinks about these two issues. It seems to me that the hardest part is dealing with drivers/subsystems that have no runtime PM support. In such cases, we have to be very careful not to use direct_complete unless we know that the device does no power management at all. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
