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From: Peter Hutterer <peter.hutterer@who-t.net>
To: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Henrik Rydberg <rydberg@bitmath.org>,
	Andi Shyti <andi@etezian.org>,
	Stephan Gerhold <stephan@gerhold.net>,
	linux-input@vger.kernel.org, Javi Ferrer <javi.f.o@gmail.com>
Subject: Re: [PATCH] Input: mms114: don't report 0 pressure while still tracking contact(s)
Date: Fri, 26 Jun 2020 10:04:39 +1000	[thread overview]
Message-ID: <20200626000439.GA108136@koala> (raw)
In-Reply-To: <20200623182540.0ed5de81@primarylaptop.localdomain>

On Tue, Jun 23, 2020 at 06:25:45PM +0200, Denis 'GNUtoo' Carikli wrote:
> On Mon, 15 Jun 2020 09:57:35 +1000
> Peter Hutterer <peter.hutterer@who-t.net> wrote:
> > > > Event: time 1585880998.920994, type 3 (EV_ABS), code 57
> > > > (ABS_MT_TRACKING_ID), value 0 Event: time 1585880998.920994, type
> > > > 3 (EV_ABS), code 53 (ABS_MT_POSITION_X), value 400 Event: time
> > sorry, but this is completely unreadable. Please make sure it's in the
> > originally formatting that evtest/evemu/libinput record spit out.
> > Thanks.
> Indeed.
> 
> I'm sorry about that, I didn't see it while sending the mail.

thanks for the log. Basically - the problem is that ABS_MT_TOUCH_MAJOR and
ABS_PRESSURE are completely unrelated on the device and the latter has
apparently random values. 1585880999.248531 is an event where you go from
almost max pressure to 0 without changing touch major.

Since pressure is more common, you'll have to expect that userspace may
ignore major/minor and handle pressure instead where available. Doubly so
since historically the major/minor value range has been completely random
while pressure was at least somewhat predictable. In this sequence, your
touch major ranges from 4-14 despite the axis range being 0-255.

Historically, pressure has also been used as equivalent to touch size, so
decoupling touch size and pressure is tricky anyway. Speaking from
libinput's POV I would disable ABS_(MT_)PRESSURE in this device since it's
not reliable to detect a touch. But then we'd still need a quirk in place to
tell us what the possible touch major range could be to make sense of that
number.

Cheers,
   Peter

> Event: time 1585880999.248531, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 1210
> Event: time 1585880999.248531, type 3 (EV_ABS), code 48 (ABS_MT_TOUCH_MAJOR), value 14
> Event: time 1585880999.248531, type 3 (EV_ABS), code 58 (ABS_MT_PRESSURE), value 244
> Event: time 1585880999.248531, type 3 (EV_ABS), code 1 (ABS_Y), value 1210
> Event: time 1585880999.248531, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 244
> Event: time 1585880999.248531, -------------- SYN_REPORT ------------
> Event: time 1585880999.259798, type 3 (EV_ABS), code 54 (ABS_MT_POSITION_Y), value 1208
> Event: time 1585880999.259798, type 3 (EV_ABS), code 58 (ABS_MT_PRESSURE), value 0
> Event: time 1585880999.259798, type 3 (EV_ABS), code 1 (ABS_Y), value 1208
> Event: time 1585880999.259798, type 3 (EV_ABS), code 24 (ABS_PRESSURE), value 0
> Event: time 1585880999.259798, -------------- SYN_REPORT ------------

  reply	other threads:[~2020-06-26  0:04 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-06  3:50 [PATCH] Input: mms114: don't report 0 pressure while still tracking contact(s) Denis 'GNUtoo' Carikli
2020-06-06 18:18 ` Dmitry Torokhov
2020-06-08  1:06   ` Peter Hutterer
2020-06-12 17:46   ` Denis 'GNUtoo' Carikli
2020-06-14 23:57     ` Peter Hutterer
2020-06-23 16:25       ` Denis 'GNUtoo' Carikli
2020-06-26  0:04         ` Peter Hutterer [this message]
2020-07-26 21:42           ` Denis 'GNUtoo' Carikli
2020-09-07  3:06             ` Peter Hutterer

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