From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [linux-pm] [PATCH v2 1/2] Input: gpio-keys - allow platform to specify exact irq flags Date: Wed, 9 Dec 2009 10:03:45 -0800 Message-ID: <20091209180345.GE4456@core.coreip.homeip.net> 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> <1260343860.19669.1189.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pz0-f171.google.com ([209.85.222.171]:38752 "EHLO mail-pz0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755784AbZLISDv (ORCPT ); Wed, 9 Dec 2009 13:03:51 -0500 Received: by pzk1 with SMTP id 1so29030pzk.33 for ; Wed, 09 Dec 2009 10:03:58 -0800 (PST) Content-Disposition: inline In-Reply-To: <1260343860.19669.1189.camel@localhost> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Artem Bityutskiy Cc: Pavel Machek , Ferenc Wagner , Alan Stern , linux-pm@lists.linux-foundation.org, Mika Westerberg , "linux-input@vger.kernel.org" On Wed, Dec 09, 2009 at 09:31:00AM +0200, Artem Bityutskiy wrote: > 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. But the semantics are different - if done on driver level you'd be affecting _all_ consumers of the device; what I want to be done only affects owner of the file descriptor. -- Dmitry