linux-kernel - Re: [Letux-kernel] [PATCH v9 1/8] drivers:input:tsc2007: add new common binding names, pre-calibration, flipping and rotation

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Message-ID: <20170221180755.48946fc5@aktux>
Date:   Tue, 21 Feb 2017 18:07:55 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     "H. Nikolaus Schaller" <hns@...delico.com>,
        Mark Rutland <mark.rutland@....com>,
        Andrey Gelman <andrey.gelman@...pulab.co.il>,
        Michel Verlaan <michel.verl@...il.com>,
        Nick Dyer <nick@...anahar.org>,
        Tony Lindgren <tony@...mide.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Pavel Machek <pavel@....cz>,
        Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>,
        Aaro Koskinen <aaro.koskinen@...ia.com>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Igor Grinberg <grinberg@...pulab.co.il>,
        Hans Verkuil <hans.verkuil@...co.com>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Eric Engestrom <eric@...estrom.ch>,
        Hans de Goede <hdegoede@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Petr Cvek <petr.cvek@....cz>,
        Siebren Vroegindeweij <siebren.vroegindeweij@...mail.com>,
        Haibo Chen <haibo.chen@...escale.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Sebastian Reichel <sre@...nel.org>, linux-iio@...r.kernel.org,
        "Andrew F. Davis" <afd@...com>, Mark Brown <broonie@...nel.org>,
        Benoît Cousson <bcousson@...libre.com>,
        kernel@...a-handheld.com, Michael Welling <mwelling@...e.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Alexander Stein <alexander.stein@...tec-electronic.com>
Subject: Re: [Letux-kernel] [PATCH v9 1/8] drivers:input:tsc2007: add new
 common binding names, pre-calibration, flipping and rotation

Hi,

[...]
> > Hm. Why not touching pixel (0,0) on the touch is always pixel (0,0)
> > on the screen and touching pixel (639,479) is always (639,479)?
> 
> Important is that there is no 1:1 mapping between input evdev device
> and drm/fb output device. These are two independent devices. There is
> no connection between screen and touch. So such presumption should
> not be done in kernel. You can do that in userspace.
> 
But at least it can be told to userspace that these two devices are
connected. That information should be specified in devicetree because
it is not auto-detectable.

> Lets take e.g. touchpad. It acts similarly as touchscreen input device
> (both reports absolute positioned touch events), but touchpad is not
> connected with screen. And from kernel point of view these devices are
> both input and absolute positioned.
> 
> It looks like the whole problem is there that you wanted to do this
> mapping for your hardware in kernel. And this is not what is kernel
> doing or should do. Moreover I know people who are using integrated
> touchscreen on laptop as (touch) input device for external monitor.
> And in this configuration it does not make any sense to map
> touchscreen input to pixels of integrated LCD touchscreen (as
> external monitor could have different resolution as integrated LCD
> touchcreen).
>   
Interesting example. But then you also do not need flipping/rotation
because the angle between your screen and your absolute position device
is not fixed.

Regards,
Andreas

>

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