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

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Message-ID: <20170218032233.3qh5xdjbx5kkq5hm@earth>
Date:   Sat, 18 Feb 2017 04:22:33 +0100
From:   Sebastian Reichel <sre@...nel.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     "H. Nikolaus Schaller" <hns@...delico.com>,
        Mark Rutland <mark.rutland@....com>,
        Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        Michael Welling <mwelling@...e.org>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Igor Grinberg <grinberg@...pulab.co.il>,
        "Andrew F. Davis" <afd@...com>, Mark Brown <broonie@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Alexander Stein <alexander.stein@...tec-electronic.com>,
        Eric Engestrom <eric@...estrom.ch>,
        Hans de Goede <hdegoede@...hat.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Petr Cvek <petr.cvek@....cz>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Nick Dyer <nick@...anahar.org>,
        Siebren Vroegindeweij <siebren.vroegindeweij@...mail.com>,
        Michel Verlaan <michel.verl@...il.com>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        letux-kernel@...nphoenux.org, linux-iio@...r.kernel.org,
        kernel@...a-handheld.com, Aaro Koskinen <aaro.koskinen@...ia.com>,
        Pali Rohár <pali.rohar@...il.com>,
        Pavel Machek <pavel@....cz>,
        Andrey Gelman <andrey.gelman@...pulab.co.il>,
        Haibo Chen <haibo.chen@...escale.com>
Subject: Re: [PATCH v9 1/8] drivers:input:tsc2007: add new common binding
 names, pre-calibration, flipping and rotation

Hi,

On Fri, Feb 17, 2017 at 12:40:41PM -0800, Dmitry Torokhov wrote:
> > AFAIK there is no mainline board using the DT except ours (and the upcoming
> > OMAP5-Pyra), so we shouldn't care too much. If you prefer, you can remove this
> > compatibility property. We don't need it for our devices.

$ cd linux.git/arch
$ git grep -l tsc2004
arm/boot/dts/imx6qdl-nit6xlite.dtsi
arm/boot/dts/imx7d-nitrogen7.dts
arm/boot/dts/logicpd-torpedo-37xx-devkit.dts
arm/boot/dts/omap4-var-som-om44.dtsi
$ git grep -l tsc2005
arm/boot/dts/omap3-n900.dts
$ git grep -l tsc2007
arm/boot/dts/imx28-tx28.dts
arm/boot/dts/imx35-eukrea-cpuimx35.dtsi
arm/boot/dts/imx51-eukrea-cpuimx51.dtsi
arm/boot/dts/imx53-tx53-x03x.dts
arm/boot/dts/imx6qdl-tx6.dtsi
arm/boot/dts/imx6ul-tx6ul.dtsi
arm/boot/dts/omap3-gta04.dtsi
sh/boards/mach-ecovec24/setup.c

> You seem to be treating DT data as something very fluid, which is wrong.
> You need to treat it as a firmware, unlikely to change once device is
> shipped. Unlike legacy platform data, the fact that DTS files are not
> present in mainline does not mean that we can ignore such users and
> change behavior at will.
> 
> That said, if driver behavior is out of line from the subsystem
> expectations, we need to fix it.
> 
>  
> > That the function name is wrong is a second issue and this double negation might
> > confuse a litte.
> > 
> > Please test on a real device if the patched driver reports pressure now (unless
> > ti,report-resistance is specified).
> 
> I unfortunately can not test this driver as I do not have the hardware.
> So all my observations are from code and data sheets.
> 
> That said, what is the values emitted as ABS_PRESSURE when finger is not
> touching the device, barely touching the device, or pressing firmly?
> It seems that between TSC2007, TSC2004, TSC2005, and ADS7846, we have
> confusion as to what is being reported.

As far as I can see all calculate Rtouch and ADS7846 reports
(Rmax - Rtouch), which looks sensible.

> I am adding a few more folks to the CC so we can try and soft this out.
> Sebastian, Pali, Pavel, any input here?

I think tsc200x works, since usually userspace is Xorg and I think
it only cares for x/y coordinates + boolean pressure. Since
no-pressure is correctly reported as 0, everything works as
expected. I currently don't have X running on my N900 due some
omapdrm bug, so I can't test this, sorry.

I suggest to put the resistance vs pressure thing in its own patch,
that also fixes tsc200x-core and merge it to linux-next after the
merge window.

-- Sebastian

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