From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] input : wacom - report resolution for ABS_MT events Date: Fri, 28 Jan 2011 11:37:31 -0800 Message-ID: <20110128193731.GH6252@core.coreip.homeip.net> References: <1296179245-14614-1-git-send-email-pinglinux@gmail.com> <20110128173048.GC2586@polaris.bitmath.org> <20110128184654.GG6252@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:52352 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751556Ab1A1Thn (ORCPT ); Fri, 28 Jan 2011 14:37:43 -0500 Received: by gxk9 with SMTP id 9so1211841gxk.19 for ; Fri, 28 Jan 2011 11:37:42 -0800 (PST) Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Ping Cheng Cc: Henrik Rydberg , linux-input@vger.kernel.org On Fri, Jan 28, 2011 at 11:01:39AM -0800, Ping Cheng wrote: > On Fri, Jan 28, 2011 at 10:46 AM, Dmitry Torokhov > wrote: > > On Fri, Jan 28, 2011 at 10:23:59AM -0800, Ping Cheng wrote: > >> On Fri, Jan 28, 2011 at 9:30 AM, Henrik Rydberg wrote: > >> > Hi Ping, > >> > > >> >> This is mainly required by the serial pen and touch devices sin= ce > >> >> both pen and touch are on the same port. Updated the USB ones t= o > >> >> keep MT event definition consistent among serial and USB device= s. > >> > > >> > Why is this change performed? What does the patch do? Please ela= borate > >> > a little bit. > >> > >> Let's see if I can explain it clearer or not. > >> > >> We need to report resolution to userland for wacom_w8001.c. Since = pen > >> and touch data are reported through the same logical port for seri= al > >> devices, using input_abs_set_res =A0for ABS_X/Y, =A0we can only pa= ss the > >> resolution for pen or touch. So, I let ABS_X/Y report pen resoluti= on > >> since most legacy ST clients process pen data over touch. However,= for > >> multi-touch clients, especially for those that support gestures, t= ouch > >> resolution is needed to calculate the physical distance between tw= o > >> touch points. Using =A0ABS_MT_POSITION_X/Y does not cause confusio= n and > >> it is quite intuitive. > > > > We just went through the round of why we should scale events from > > different tools when they use the same event devices and I do not s= ee > > why MT data is any different. >=20 > At the time when we worked on that, we did not consider resolution. W= e > only scaled the logical values. >=20 > > Devices have only one set of physical axes (MT or not) >=20 > You are right if the device only supports one type of tools. Yes, ST > or pen can go with ABS_X/Y. MT goes with MT. However, we are dealing > with a dual tool case: pen and touch on the same port. Using only one > set of axes would not be able to cover both tool events and pass the > resolution to the userland. >=20 > > so I believe > > min, max and resultion should be reported on ABS_X, Y, X, etc, or, = if > > you want to have this data in ABS_MT_POSITION, it should be trhe sa= me. >=20 > max/min is different from resolution. We can scale max/min since they > are logical data. But we can not change the device's physical size. > That's the root cause of the "stubborn" nature of resolution. This is the same device so it should have the same physical dimensions, right? --=20 Dmitry -- 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