From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] Input: mt: only perform pointer emulation on drivers desiring this functionality Date: Thu, 27 Oct 2016 16:54:06 -0700 Message-ID: <20161027235406.GE12312@dtor-ws> References: <1477603873-9143-1-git-send-email-roderick@gaikai.com> <20161027231942.GB12312@dtor-ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:36180 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933978AbcJ0XyK (ORCPT ); Thu, 27 Oct 2016 19:54:10 -0400 Received: by mail-pf0-f195.google.com with SMTP id n85so3855774pfi.3 for ; Thu, 27 Oct 2016 16:54:10 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Roderick Colenbrander Cc: linux-input@vger.kernel.org, Henrik Rydberg , Benjamin Tissoires , Tim Bird , Roderick Colenbrander On Thu, Oct 27, 2016 at 04:46:01PM -0700, Roderick Colenbrander wrote: > On Thu, Oct 27, 2016 at 4:19 PM, Dmitry Torokhov > wrote: > > On Thu, Oct 27, 2016 at 02:31:13PM -0700, Roderick Colenbrander wrote: > >> From: Roderick Colenbrander > >> > >> The input-mt driver pointer emulation from 'input_mt_sync_frame' regardless > >> of the flags passed in to 'input_mt_init_slots' by device drivers. > > > > Right, because needing single-touch (pointer) emulation is not property > > of device or driver but rather consumer. If we get to the point where > > everything is ready to accept multi-touch (are we there yet) then we can > > stop doing pointer emulation altogether. > > > >> > >> Pointer emulation is undesired on drivers, which didn't request this > >> capability like the hid-sony driver for the Dualshock 4. This gamepad already > >> reports ABS_X / ABS_Y for gamepad stick purposes. Pointer emulation would > >> inject touchpad values into these sticks, which is undesired. > > > > The driver should not be re-purposing events like that. > > ABS_MT_POSITION_X and ABS_X should match. > > > > Why doesn't driver follow Documentation/input/gamepad.txt? > > > > The original hid-sony code and the multitouch handling code for the Dualshock 4 > were written by the community. We are stepping in to make the hid-sony driver > properly handle the Dualshock 4. > The driver doesn't fully follow the gamepad spec yet, which we will > try to improve. At > least the left analog stick is reported as ABS_X and ABS_Y already, > but the buttons > are inconsistent and right stick is wrong as well. > While it would be great to conform to the spec, the conflict with > multitouch would still > exist as the Dualshock 4 has both analog sticks and a multitouch touchpad. > > Disabling the pointer emulation feature avoids the conflict. This > issue was only exposed > recently by adding of the input_mt_sync_frame call as recommended by Benjamin as > part of some improvements we did for touchpad handling in hid-sony. As I mentioned, ABS_MT_POSITION_X and ABS_X should represent the same data, so the driver's use of them for different sub-devices is not correct. Maybe the multitouch "touchpad" should be reported as completely separate input device and userspace should "stitch" it back into composite device. In any case, as I mentioned above, the pointer emulation is requirement of client and thus this patch is not appropriate. Thanks. -- Dmitry