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: <EE81034E-C10E-4E8B-B026-B3E92C0DAA19@goldelico.com>
Date:   Mon, 20 Feb 2017 17:50:28 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Andreas Kemnade <andreas@...nade.info>,
        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>, linux-kernel@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        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, devicetree@...r.kernel.org,
        Pali Rohár <pali.rohar@...il.com>,
        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>,
        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 Pavel,

> Am 19.02.2017 um 23:39 schrieb Pavel Machek <pavel@....cz>:
> 
> Hi!
> 
>>>> And note that I am not making things different from others in tree,
>>>> I am making the tsc2007 right (incl. following the touchscreen
>>>> bindings which define the touchscreen size in "Pixels").
>>> 
>>> Your touch screen is not in any way special, so it has to behave in
>>> the same way others do.
>>> 
>> 
>> I agree, the tsc2007 (=what the interface provides to userspace) should
>> not behave special, for example it should behave like the virtual
>> touchscreen (=what the interface provides to userspace) virtualbox
>> gives. No need to be calibrated. Well, the internals are different. But
>> that is what the kernel is good for, abstract such things.
>> Conclusion: It cannot be totally wrong behavior to have pixel values
>> there.
> 
> It is not "totally wrong". But it is useless code that should not be
> in kernel. Calibration certainly does not belong to single
> _driver_.

It belongs to driver + attached panel. I.e. hardware. Which the kernel
or driver should IMHO abstract from as good as possible.

> Feel free to submit driver

For what? The tsc2007 driver already exists.

> but keep the calibration code out
> of tree...

It is the really important patch to add this.

> 
> But if you have userspace that depends on touchscreen to be
> calibrated... that _is_ wrong.

User-space people and real users have the opposite opinion. They
prefer if a touch is plug&play. I.e. without need for calibration.

When did you last time re-calibrate the heads of your hard disk in
user-space?

BR and thanks,
Nikolaus


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