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From: Jonathan Denose <jdenose@chromium.org>
Date: Fri, 12 Jan 2024 09:10:47 -0600
Message-ID: <CALNJtpUrevm6YXZjG=37H4vs4_1RbHsO6BgsoQbUjZQHzpSOJA@mail.gmail.com>
Subject: Re: [PATCH] Input: i8042 - add quirk for Lenovo ThinkPad T14 Gen 1
To: Hans de Goede <hdegoede@redhat.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>, linux-input@vger.kernel.org, 
	Jonathan Denose <jdenose@google.com>, Huacai Chen <chenhuacai@kernel.org>, 
	Mattijs Korpershoek <mkorpershoek@baylibre.com>, Takashi Iwai <tiwai@suse.de>, 
	Werner Sembach <wse@tuxedocomputers.com>, linux-kernel@vger.kernel.org
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Hans,

On Thu, Jan 11, 2024 at 4:48=E2=80=AFAM Hans de Goede <hdegoede@redhat.com>=
 wrote:
>
> Hi Jonathan,
>
> On 1/11/24 00:42, Jonathan Denose wrote:
> > Dmitry,
> >
> > Sorry I forgot to reply all, so I'm resending my other email.
> >
> > On Tue, Jan 9, 2024 at 1:28=E2=80=AFPM Dmitry Torokhov
> > <dmitry.torokhov@gmail.com> wrote:
> >>
> >> Hi Jonathan,
> >>
> >> On Mon, Nov 27, 2023 at 10:38:57AM -0600, Jonathan Denose wrote:
> >>> Hi Dmitry
> >>>
> >>> On Fri, Nov 24, 2023 at 10:45=E2=80=AFPM Dmitry Torokhov
> >>> <dmitry.torokhov@gmail.com> wrote:
> >>>>
> >>>> Hi Jonathan,
> >>>>
> >>>> On Mon, Sep 25, 2023 at 04:33:20PM -0500, Jonathan Denose wrote:
> >>>>> The ThinkPad T14 Gen 1 touchpad works fine except that clicking
> >>>>> and dragging by tapping the touchpad or depressing the touchpad
> >>>>> do not work. Disabling PNP for controller setting discovery enables
> >>>>> click and drag without negatively impacting other touchpad features=
.
> >>>>
> >>>> I would like to understand more on how enabling PnP discovery for i8=
042
> >>>> affects the touchpad. Do you see it using different interrupt or IO
> >>>> ports? What protocol does the touchpad use with/without PnP? If the
> >>>> protocol is the same, do you see difference in the ranges (pressure,
> >>>> etc) reported by the device?
> >>>>
> >>>> Thanks.
> >>>>
> >>>> --
> >>>> Dmitry
> >>>
> >>> Without PnP discovery the touchpad is using the SynPS/2 protocol, wit=
h
> >>> PnP discovery, the touchpad is using the rmi4 protocol. Since the
> >>> protocols are different, so are the ranges but let me know if you
> >>> still want to see them.
> >>
> >> Thank you for this information. So it is not PnP discovery that appear=
s
> >> harmful in your case, but rather that legacy PS/2 mode appears to be
> >> working better than RMI4 for the device in question.
> >>
> >> I will note that the original enablement of RMI4 for T14 was done by
> >> Hans in [1]. Later T14 with AMD were added to the list of devices that
> >> should use RMI4 [2], however this was reverted in [3].
> >>
> >> Could you please tell me what exact device you are dealing with? What'=
s
> >> it ACPI ID?
> >>
> >> [1] https://lore.kernel.org/all/20201005114919.371592-1-hdegoede@redha=
t.com/
> >> [2] https://lore.kernel.org/r/20220318113949.32722-1-snafu109@gmail.co=
m
> >> [3] https://lore.kernel.org/r/20220920193936.8709-1-markpearson@lenovo=
com
> >>
> >> Thanks.
> >>
> >> --
> >> Dmitry
> >
> > Thanks for your reply!
> >
> > I'm not 100% sure which of these is the ACPI ID, but from `udevadm
> > info -e` there's:
> > N: Name=3D"Synaptics TM3471-020"
> > P: Phys=3Drmi4-00/input0
>
> To get the ACPI ID you need to run e.g. :``
>
> cat /sys/bus/serio/devices/serio1/firmware_id
>
> After reading the original bug report again I take back my
> Reviewed-by and I'm tending towards a nack for this.
>
> Jonathan upon re-reading things I think that your problem
> is more a case of user space mis-configuration then
> a kernel problem.
>
> You mention both tap-n-drag not working as well as click+drag
> not working.
>
> tap-n-drag is purely done in userspace and typically only
> works if tap-to-click is enabled in the touchpad configuration
> of your desktop environment.
>
> Click + drag requires you to use the bottom of the touchpad
> (the only part which actually clicks) as if there still were
> 2 physical buttons there and then click the touchpad down
> with 1 finger till it clicks and then drags with another
> finger (you can click+drag with one finger but the force
> required to keep the touchpad clicked down while dragging
> makes this uncomfortable to do).
>
> This will likely also only work if the mouse click emulation
> mode is set to "area" and not "fingers" with "fingers" being
> the default now. In GNOME you can configure
> the "click emulation mode" in the "tweaks" tools under
> "mouse & touchpad" (and tap to click is in the normal
> settings menu / control panel).
>
> If you have the click emulations set to fingers and
> then do the click with 1 finger + drag with another
> finger thing, I think the drag will turn into a
> right button drag instead of a left button drag which
> is likely why this is not working.
>
> You can check which mode you are in by seeing how
> you right click. If you right-click by pressing down
> in the right bottom corner of the touchpad then
> your userspace (libinput) config is set to areas,
> if you can right click anywhere by pressing down
> with 2 fingers at once then your click emulation
> is in fingers mode and this is likely why click-n-drag
> is not working.
>
> I have just dug up my T14 gen1 (Intel) and updated it
> to kernel 6.6.11 to rule out kernel regressions.
>
> And both click-n-drag and tap-n-drag (double-tap then
> drag) both work fine there with a touchpad with
> an ACPI id of LEN2068 as shown by
> cat /sys/bus/serio/devices/serio1/firmware_id
>
> (with the Desktop Environment configured for bottom
> area click emulation and tap-to-click enabled)
>
> As for why changing things back to synps2 works,
> I don't know. One guess is that you already configured
> the touchpad behavior of your desktop environment to
> your liking in the past and your desktop environment
> has remembered this only for the input device-name
> which is used in SynPS/2 mode and the different
> input device-name in RMI4 mode in new (new-ish)
> kernels causes the desktop environment to use
> default settings which are typically "fingers"
> click emulation and tap-to-click disabled.
>
> This can e.g. also happen if you have moved your
> disk (contents) over from an older machine. IIRC
> the SynPS/2 driver always used the same input
> device-name where as with RMI4 the name is tied
> to the actual laptop model.
>
> Regards,
>
> Hans
>
>

Thank you for your thorough reply. Based on what you've written, I
agree this sounds more like a user-space issue than a kernel issue. At
least that narrows it down for me, so I'll take a look at what could
be misconfigured in user-space.

Thanks so much for your help!
Jonathan