On Tue, 2009-12-08 at 09:42 -0800, Dmitry Torokhov wrote: > > > I also see that gpio-keys is quite different in the sence that it can > > > shut off buttons selectively. I fact, at the moment every button can be > > > considered a separate device... But that would be too much overhead. > > > > > > They could probably split the keys into 2 groups (critical that should > > > be always active) and not critical, that could be shut off, but I think > > > they want teh flexibility of controlling this at runtime instead of > > > doing it in board data. > > > > I suggested including this into the "abstract input device" model, but > > you refuse this. But I still think it is a good idea. > > > > Indeed, if we look at an input device as at something abstract which has > > many keys, why we cannot assume that separate keys can be > > enabled/disabled? Just imagine you have a very advanced keybord :-) And > > we simply implement an ioctl which enables/disables a specific key. The > > generic layers just pass this ioctl down to the lower lever drivers. If > > the specific input device or driver support it - fine, if not - it > > returns -EINVAL or something like that. > > I refuse it because it will be supported by exactly 1 driver in the > kernel - gpio-keys. It is the only driver that allows shut half of the > "device" (because in reality it is a group of disjoint devices). It is > the only case when "muting" a button means that IRQ is shut off abnd > thus CPU can continue to sleep if that button is pressed. For all other > devices that have 1 inettrupt per device, you still have to wake up, > because you don't know whether the button that generated event is > "important" or not. Fair enough. > Now, there is a issue of waking up userspace task, additional scheduling > and keeping CPU running longer than necessary for "uninteresting" keys. > This can be solved by implementing a subscription model which allows > filtering uninteresing events on a per-client basis at evdev level. Right. And for gpio_keys, this would be dine on the driver level. > This, if implemented properly, would work for _all_ input devices out > there. You were not interested into looking into it (because for your > particular and only device the otehr approach promises bigger savings) > but I think we'll get there eventually. Well, we can (and have to, if this approach is taken) look into this in a sense of implementing our particular task in a way that it could be extended with this generic stuff. We might as well implement something generic, but may be not too comprehensive, feature-full, and well-tested (simply because we do not need it, so cannot prove usefulness on real applications). > And the third topic - shutting (or putting into low power) entire device > upon request from userspace. This again has much wider auditory than > gpio-keys, or input devices layer for that matter. We may want to do so > for other types of devices as well. That is why the question when to > general PM list. Yeah. -- Best Regards, Artem Bityutskiy (Артём Битюцкий) _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
