linux-kernel - Re: [PATCH v3] Input: rename INPUT_PROP_HAPTIC_TOUCHPAD to INPUT_PROP

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Message-ID: <2khyn7qnwphg6hinptwsfs3xnn64nsitebja3sqnolceopwylg@mqrq3duv3nel>
Date: Mon, 17 Nov 2025 23:38:06 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Peter Hutterer <peter.hutterer@...-t.net>
Cc: Jonathan Denose <jdenose@...gle.com>, Jiri Kosina <jikos@...nel.org>, 
	Benjamin Tissoires <bentiss@...nel.org>, Jonathan Corbet <corbet@....net>, 
	Henrik Rydberg <rydberg@...math.org>, linux-input@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, Angela Czubak <aczubak@...gle.com>, 
	Sean O'Brien <seobrien@...gle.com>, Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v3] Input: rename INPUT_PROP_HAPTIC_TOUCHPAD to
 INPUT_PROP_PRESSUREPAD

On Thu, Nov 06, 2025 at 09:45:34PM +1000, Peter Hutterer wrote:
> And expand it to encompass all pressure pads.
> 
> Definition: "pressure pad" as used here as includes all touchpads that
> use physical pressure to convert to click, without physical hinges. Also
> called haptic touchpads in general parlance, Synaptics calls them
> ForcePads.
> 
> Most (all?) pressure pads are currently advertised as
> INPUT_PROP_BUTTONPAD. The suggestion to identify them as pressure pads
> by defining the resolution on ABS_MT_PRESSURE has been in the docs since
> commit 20ccc8dd38a3 ("Documentation: input: define
> ABS_PRESSURE/ABS_MT_PRESSURE resolution as grams") but few devices
> provide this information.
> 
> In userspace it's thus impossible to determine whether a device is a
> true pressure pad (pressure equals pressure) or a normal clickpad with
> (pressure equals finger size).
> 
> Commit 7075ae4ac9db ("Input: add INPUT_PROP_HAPTIC_TOUCHPAD") introduces
> INPUT_PROP_HAPTIC_TOUCHPAD but restricted it to those touchpads that
> have support for userspace-controlled effects. Let's expand and rename
> that definition to include all pressure pad touchpads since those that
> do support FF effects can be identified by the presence of the
> FF_HAPTIC bit.
> 
> This means:
> - clickpad: INPUT_PROP_BUTTONPAD
> - pressurepad: INPUT_PROP_BUTTONPAD + INPUT_PROP_PRESSUREPAD
> - pressurepad with configurable haptics:
>   INPUT_PROP_BUTTONPAD + INPUT_PROP_PRESSUREPAD + FF_HAPTIC
> 
> Signed-off-by: Peter Hutterer <peter.hutterer@...-t.net>

Applied, thank you.

-- 
Dmitry