Hello Johannes, On 19 January 2016 at 15:08, Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > Hi, > >> There was a misunderstanding of these semantics on my side, despite >> this being documented in Documentation/rfkill.txt. Now I've realized >> the semantic difference between 1."having all the individual switches >> of a certain type blocked at a certain moment" and 2."blocking all >> switches of a certain type": on the 1st situation, each switch was >> individually blocked in different moments, and by chance a certain >> type had all its registered switches blocked, while on the 2nd, all >> switches of a certain type were blocked altogether using >> RFKILL_OP_CHANGE_ALL. Only on the 2nd situation we want to update the >> default state for hotplugged devices, and that's why >> rfkill_global_states[type] is not updated when individual switches >> are >> driven, even if we read situation 1. Then there is actually no >> difference between the state value and the operation, and there is >> nothing to be fixed on an individual switch change. Sorry for the >> confusion. > > Ok, glad you have that cleared up because I'm not sure I understand > what you were confused about :) > >> I'm going to add a note about this behavior to >> include/uapi/linux/rfkill.h as well. > > If it helps the next person, sure! > >> > * allow only a single userspace owner, and require that owner to >> > toggle it as required, to avoid multiple userspace applications >> > stepping on each others' toes. This could be implemented by >> > making >> > this a new /dev/rfkill command, and requiring the fd to be held >> > open while controlling the airplane mode state. >> > >> >> And when the fd gets released we would fallback to default, right? > > Yeah, I guess so. Something has to be known to be controlling it, and > two applications can't really do it at the same time. > Ack. >> So >> that would avoid two userpace apps trying to control it at the same >> time, but not one after the other (which is a good thing). As I >> understand it also implies we would not expose this control point >> through sysfs. > > Yes, and I agree, sysfs wouldn't make a lot of sense for this (since > you can't track ownership that way.) > Yes, that's what I thought. >> Great, I already fixed the previous comments and started working on a >> prototype of the second stage, but then a naming question came to my >> mind. They way I'm designing it is to have only one trigger and >> change >> its behavior when the "airplane mode indicator" is under userspace >> control (basically changing when to call led_trigger_event() to fire >> the trigger). In this case it probably makes sense to call the >> trigger >> something like "rfkill-airplane_mode", as before, because it will >> fire when we're in an "airplane safe" mode, controlled by userspace >> or with a fallback default behavior. > > Sure. > Ack. >> Another option would be to have two separate triggers, >> "rfkill-airplane_mode" controlled by userspace, and "rfkill-all" >> implementing the default behavior, and change which trigger is set to >> each LED *from the trigger implementation side* in rfkill. Unless I'm >> missing something, I don't think this second approach is possible. > > Yes, this doesn't make sense. > Ok, good to know :) >> So the question is, if we go with the 1st approach, would it be fine >> to call the trigger "rkill-airplane_mode", even for the first stage >> when only the default behavior is implemented, or should I rename it >> (which implies renaming an API to other drivers) during the 2nd stage >> implementation? I think sticking with one name from the beginning is >> better, but since it goes against previous feedback, I decided to ask >> first. > > Indeed, I think it's better. I wasn't previously considering (much) the > possibility of enhancing the framework :) > > Thanks for your work on this - I see also your patches already, will go > over them soon; I'm working part-time on parental leave right now, so things take a bit longer than usual. > Thanks for the clarifications! I'll clean-up the patches that actually implement this (the ones I've send are only general fixes/improvements) and send them in the next days. Don't worry about delays, enjoy your parental leave! -- João Paulo Rechi Vita http://about.me/jprvita -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
