linux-kernel - Re: [RFC v1 0/4] Input: support virtual objects on touchscreens

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Message-ID: <ZEp1Z08/CQ+waw8+@duo.ucw.cz>
Date:   Thu, 27 Apr 2023 15:15:19 +0200
From:   Pavel Machek <pavel@....cz>
To:     Michael Riesch <michael.riesch@...fvision.net>
Cc:     Javier Carrasco <javier.carrasco@...fvision.net>,
        phone-devel@...r.kernel.org, linux-input@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Henrik Rydberg <rydberg@...math.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Stephen Boyd <sboyd@...nel.org>,
        Sebastian Reichel <sre@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Uwe Kleine-g <u.kleine-koenig@...gutronix.de>,
        Bastian Hecht <hechtb@...il.com>
Subject: Re: [RFC v1 0/4] Input: support virtual objects on touchscreens

Hi!

> > 
> >> Some touchscreens are shipped with a physical layer on top of them where
> >> a number of buttons and a resized touchscreen surface might be
> >> available.
> > 
> > Yes, it is quite comon, for example Motorola Droid 4 has 4 virtual
> > buttons below touchscreen.
> 
> Are those buttons configurable in some way? Or do they have a fixed purpose?

Fixed.

> How does Android handle those buttons, BTW?

No idea.

> > One question is if this should be handled inside the kernel. It will
> > make it compatible with existing software, but it will also reduce
> > flexibility.
> 
> I would say that it should be described in device tree if the purpose is
> fixed. For example, if there is no display behind the touch screen at a
> certain point but a printed sheet (e.g., with a home or return symbol)
> then it is clear that this button is not going to change. In such a case
> I doubt that flexibility is required.

I agree it should be in the device tree.

AFAICT hardware can do drags between the buttons, and drag between the
buttons and touchscreen. Turning it into buttons prevents that.

Plus, real buttons can do simultaneous presses on all of them,
touchscreens will have problems with that.

Best regards,
								Pavel
-- 
People of Russia, stop Putin before his war on Ukraine escalates.

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