On Friday, 3 August 2007 16:56, Alan Stern wrote: > On Fri, 3 Aug 2007, Rafael J. Wysocki wrote: > > > > > Why not? If the device can indicate something like "place me after that one" > > > > to the code creating the list, we can handle that too. > > > > > > Yes, but currently we don't have any way of indicating that. And if we > > > did, it work work just as well with the current dpm_active list, right? > > > > Well, I don't know. :-) > > > > It seems the problem is _exactly_ that we have no means to represent the > > dependencies between devices other than the order of registration and/or > > the parent-child relationships. > > Yes. > > > Now, the simplest things that comes to mind is to do what we're doing (ie. > > use the order of registration) with a modification allowing the exceptional > > devices to have a "please move me to the end of list" flag set. The PM core > > would then browse the list during suspend and move the devices marked like > > this to the end of dpm_active along with their children, if need be. > > Code is more flexible than flags. Why not export a function drivers > can call, or better yet, a handful of functions to do different things? Yes, we can do that. > It ought to suffice for drivers to call them during probing or > registration, rather than every time the system is suspended. They > also could be called after device_move() -- and to prevent races we > should export pm_sleep_[un]lock(). Yes, we should. > Suggested functions: > > 1. Move A in front of B, together with all of A's ancestors which > aren't already ahead of B (or maybe require that A's parent be > ahead of B already). > > 2. Move device A to the end (A must not have any children). > > Anything else? Nothing more comes to mind at the moment. > I think this will cover all the cases we currently are concerned about. I agree. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
