linux-kernel - Re: [PATCH 1/4] Input: Add trackpoint doubletap and system debug info keycodes

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Message-ID: <Zh2BiqQdM7_n-Ih4@google.com>
Date: Mon, 15 Apr 2024 12:35:38 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: Mark Pearson <mpearson-lenovo@...ebb.ca>,
	Peter Hutterer <peter.hutterer@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Henrique de Moraes Holschuh <hmh@....eng.br>,
	ibm-acpi-devel@...ts.sourceforge.net,
	"platform-driver-x86@...r.kernel.org" <platform-driver-x86@...r.kernel.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Nitin Joshi1 <njoshi1@...ovo.com>,
	Vishnu Sankar <vsankar@...ovo.com>
Subject: Re: [PATCH 1/4] Input: Add trackpoint doubletap and system debug
 info keycodes

On Thu, Apr 11, 2024 at 02:30:35PM +0200, Hans de Goede wrote:
> Hi Dmitry,
> 
> On 4/11/24 2:02 AM, Dmitry Torokhov wrote:
> > On Tue, Apr 09, 2024 at 10:17:05PM -0400, Mark Pearson wrote:
> >> Hi Dmitry
> >>
> >> On Tue, Apr 9, 2024, at 9:20 PM, Dmitry Torokhov wrote:
> >>> 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).
> >>>
> >>
> >> That's a somewhat disappointing note on your doubts, is that based on
> >> anything? Just wondering what we've done to deserve that criticism.
> > 
> > Sorry, this was not meant as a criticism really, but you mentioned
> > yourself that there isn't anything in the works yet, you just have some
> > plans.
> > 
> > For such a project to succeed Lenovo needs to invest into selling
> > devices with Linux as a primary operating system, and it has to be
> > consumer segment (or small business, because for corporate they
> > typically roll their own support channels). The case of retrofitting
> > Linux onto a that device originally came with Windows OS rarely gets
> > much if any response from the normal support channels.
> > 
> > Is this something that is actually happening?
> 
> Yes, Lenovo is actually offering Fedora as an OS choice when
> ordering ThinkPads directly from their website in many countries
> including when ordering as a consumer.

Ah, very nice, I was not aware of this.

> 
> And unlike other vendor's Linux preloads which often use a kernel
> with downstream laptop specific changes these laptops are running
> unmodified Fedora kernels, which themselves are almost pristine
> upstream kernels.
> 
> Lenovo (Mark) has been really good the last couple of years in
> making sure that their hw just works with mainline kernels without
> any downstream vendor specific patches.
> 
> >> That aside, I guess KEY_INFO or KEY_VENDOR could be a good fit (I
> >> personally don't think KEY_CONFIG matches well), but I would be
> >> worried about clashing with existing functionality.
> 
> Using KEY_INFO / KEY_VENDOR works for me too. So maybe we should
> just go with one of those 2 ?

It looks like Mark's preference is KEY_VENDOR, so let's go with it?

Thanks.

-- 
Dmitry