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Date: Tue, 9 Apr 2024 18:20:37 -0700
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Peter Hutterer <peter.hutterer@redhat.com>
Cc: Mark Pearson <mpearson-lenovo@squebb.ca>, hdegoede@redhat.com,
	ilpo.jarvinen@linux.intel.com, hmh@hmh.eng.br,
	ibm-acpi-devel@lists.sourceforge.net,
	platform-driver-x86@vger.kernel.org, linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org, njoshi1@lenovo.com,
	vsankar@lenovo.com
Subject: Re: [PATCH 1/4] Input: Add trackpoint doubletap and system debug
 info keycodes
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On Tue, Apr 09, 2024 at 02:47:05PM -0700, Dmitry Torokhov wrote:
> On Tue, Apr 09, 2024 at 03:23:52PM +1000, Peter Hutterer wrote:
> > On 09/04/2024 09:31, Dmitry Torokhov wrote:
> > > Hi Mark,
> > > 
> > > On Sun, Mar 24, 2024 at 05:07:58PM -0400, Mark Pearson wrote:
> > > > Add support for new input events on Lenovo laptops that need exporting to
> > > > user space.
> > > > 
> > > > Lenovo trackpoints are adding the ability to generate a doubletap event.
> > > > Add a new keycode to allow this to be used by userspace.
> > > 
> > > What is the intended meaning of this keycode? How does it differ from
> > > the driver sending BTN_LEFT press/release twice?
> > > > 
> > > > Lenovo support is using FN+N with Windows to collect needed details for
> > > > support cases. Add a keycode so that we'll be able to provide similar
> > > > support on Linux.
> > > 
> > > Is there a userspace consumer for this?
> > 
> > Funnily enough XKB has had a keysym for this for decades but it's not
> > hooked up anywhere due to the way it's pointer keys accessibility
> > feature was implemented. Theory is that most of userspace just needs
> > to patch the various pieces together for the new evdev code + keysym,
> > it's not really any different to handling a volume key (except this
> > one needs to be assignable).
> 
> What is the keysym? If we can make them relatable to each other that
> would be good. Or maybe we could find a matching usage from HID usage
> tables...

I was looking through the existing codes and I see:

#define KEY_INFO		0x166	/* AL OEM Features/Tips/Tutorial */

We also have KEY_VENDOR used in a few drivers/plafrom/x86, including
thinkkpad_acpi.c and I wonder if it would be suitable for this vendor
specific debug info collection application (which I honestly doubt will
materialize).

Thanks.

-- 
Dmitry