From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH 2/2] input: mt: Document the MT event slot protocol (rev3) Date: Sat, 22 May 2010 13:16:38 -0700 Message-ID: <20100522201637.GC30464@core.coreip.homeip.net> References: <4BF6B673.1080507@euromail.se> <20100521165218.GA26439@core.coreip.homeip.net> <4BF6BB43.2020405@euromail.se> <20100521172222.GB26439@core.coreip.homeip.net> <4BF6C303.7030804@euromail.se> <20100521174140.GA23155@core.coreip.homeip.net> <4BF6C7B6.2020008@euromail.se> <4BF7A4E8.3050806@seas.upenn.edu> <4BF7B438.8000001@euromail.se> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-px0-f174.google.com ([209.85.212.174]:64581 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755773Ab0EVUQo (ORCPT ); Sat, 22 May 2010 16:16:44 -0400 Content-Disposition: inline In-Reply-To: <4BF7B438.8000001@euromail.se> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Henrik Rydberg Cc: Rafi Rubin , Ping Cheng , Andrew Morton , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Mika Kuoppala , Peter Hutterer , Benjamin Tissoires , Stephane Chatty , Michael Poole On Sat, May 22, 2010 at 12:38:48PM +0200, Henrik Rydberg wrote: > Rafi Rubin wrote: > > On 05/21/10 13:49, Henrik Rydberg wrote: > >> Dmitry Torokhov wrote: > >>> I guess this is where our disconnect lies as when I am looking at the > >>> event names I view all *_MT_* events as related to the multitouch > >>> protocol handling. > >>> > >> Yes. It is true that slot control is MT related, but I am looking at this from > >> the perspective of future expansions like KEY_MT, KEY_REL, and such, finding a > >> way to signal to user space which events are handled via slots. If we had > >> ABS_MT_SLOT, we would most likely get applications which store ABS_MT_SLOT as an > >> attribute of the slot together with ABS_MT_POSITION_X, ABS_MT_TOUCH_MAJOR, etc, > >> which is just not right. So the proposal is ABS_SLOT. May we have your verdict, > >> please. :-) > >> > >> Henrik > >> > > > > How many fingers can type on cap of a key? > > It depends on the size of the key, does it not. :-) > > Getting serious, it is anyone's guess what will happen next, but I was picturing > a table, with a large multitouch screen and buttons along the side of the table. > Sure, we can do "ABS_BTN_0", "ABS_BTN_1", etc, but with slots in place, it seems > more natural to use something like "ABS_MT_BTN_X". While at it, REL_MT event > makes sense for those touchscreen techniques which register changes, like > acoustic pulse recognition. > While I could see relative MT events I do not understand the need for slotted key events. We already allow pressing multiple keys at once and if a device has 2 separate keys with the same event - they either should be treated as one logical key or 2 separate input devices. -- Dmitry