From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Bityutskiy Subject: Re: [linux-pm] [PATCH v2 1/2] Input: gpio-keys - allow platform to specify exact irq flags Date: Wed, 09 Dec 2009 09:31:00 +0200 Message-ID: <1260343860.19669.1189.camel@localhost> References: <87einfltp3.fsf@tac.ki.iif.hu> <20091206084704.GC2766@ucw.cz> <20091208042251.GB11147@core.coreip.homeip.net> <1260277410.19669.84.camel@localhost> <20091208174218.GB14271@core.coreip.homeip.net> Reply-To: dedekind1@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp.nokia.com ([192.100.122.233]:20722 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757199AbZLIHbj (ORCPT ); Wed, 9 Dec 2009 02:31:39 -0500 In-Reply-To: <20091208174218.GB14271@core.coreip.homeip.net> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: Pavel Machek , Ferenc Wagner , Alan Stern , linux-pm@lists.linux-foundation.org, Mika Westerberg , "linux-input@vger.kernel.org" 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 overhe= ad. > > >=20 > > > They could probably split the keys into 2 groups (critical that s= hould > > > 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. > >=20 > > I suggested including this into the "abstract input device" model, = but > > you refuse this. But I still think it is a good idea. > >=20 > > Indeed, if we look at an input device as at something abstract whic= h 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= =2E If > > the specific input device or driver support it - fine, if not - it > > returns -EINVAL or something like that. >=20 > 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 th= e > "device" (because in reality it is a group of disjoint devices). It i= s > 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 oth= er > 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. =46air enough. > Now, there is a issue of waking up userspace task, additional schedul= ing > and keeping CPU running longer than necessary for "uninteresting" key= s. > 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-teste= d (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 dev= ice > 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. --=20 Best Regards, Artem Bityutskiy (=D0=90=D1=80=D1=82=D1=91=D0=BC =D0=91=D0=B8=D1=82=D1=8E= =D1=86=D0=BA=D0=B8=D0=B9) -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html