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Date: Tue, 9 Apr 2024 15:23:52 +1000
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Subject: Re: [PATCH 1/4] Input: Add trackpoint doubletap and system debug info
 keycodes
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
 Mark Pearson <mpearson-lenovo@squebb.ca>
Cc: 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
References: <mpearson-lenovo@squebb.ca>
 <20240324210817.192033-1-mpearson-lenovo@squebb.ca>
 <20240324210817.192033-2-mpearson-lenovo@squebb.ca>
 <ZhR-WPx7dgKxziMb@google.com>
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From: Peter Hutterer <peter.hutterer@redhat.com>
In-Reply-To: <ZhR-WPx7dgKxziMb@google.com>
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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).

Cheers,
   Peter