Re: [PATCH] HID: lenovo: Detect quirk-free fw on cptkbd and stop applying workaround

[Mikhail Khvoinitsky]

Hello.

Well, that's unfortunate. As far as I can see, yes, TrackPoint
Keyboard II behaves similarly to 1st gen Trackpoint Keyboard (a.k.a.
Compact) but not quite. The best way would be to make the keyboard not
emulate scrolling at all but not sure if its possible. For cptkbd it
required patching firmware, it might be also the case for 2nd gen.

> Maybe we should map the wheel HID reports to REL_Y/REL_X in
> lenovo_input_mapping_tpIIkbd() to allow libinput to do its wheel emulation job?

It might work but since emulated wheel events aren't continuous (at
least this is the case with cptkbd), it doesn't make much sense in
comparison with the original implementation — just ignore the middle
button if scrolling.

I'll try to get the keyboard and check, but at the moment it seems
that the best thing to do is before stopping applying a workaround,
check that it's a Trackpoint Compact keyboard, not anything else. If I
won't be able to find a better solution shortly, I'll make a patch
which makes sure that it's only cptkbd before disabling the
workaround.

On Sat, 9 Dec 2023 at 20:21, Yauhen Kharuzhy <jekhor@xxxxxxxxx> wrote:
>
> On Sat, Dec 09, 2023 at 06:56:48PM +0200, Yauhen Kharuzhy wrote:
> > On Sat, Dec 09, 2023 at 02:50:16PM +0200, Yauhen Kharuzhy wrote:
> > > On Sun, Sep 24, 2023 at 01:58:30AM +0300, Mikhail Khvainitski wrote:
> > > > Built-in firmware of cptkbd handles scrolling by itself (when middle
> > > > button is pressed) but with issues: it does not support horizontal and
> > > > hi-res scrolling and upon middle button release it sends middle button
> > > > click even if there was a scrolling event. Commit 3cb5ff0220e3 ("HID:
> > > > lenovo: Hide middle-button press until release") workarounds last
> > > > issue but it's impossible to workaround scrolling-related issues
> > > > without firmware modification.
> > > >
> > > > Likely, Dennis Schneider has reverse engineered the firmware and
> > > > provided an instruction on how to patch it [1]. However,
> > > > aforementioned workaround prevents userspace (libinput) from knowing
> > > > exact moment when middle button has been pressed down and performing
> > > > "On-Button scrolling". This commit detects correctly-behaving patched
> > > > firmware if cursor movement events has been received during middle
> > > > button being pressed and stops applying workaround for this device.
> > > >
> > > > Link: https://hohlerde.org/rauch/en/elektronik/projekte/tpkbd-fix/ [1]
> > >
> > > This patch breaks a scrolling at my ThinkPad TrackPoint Keyboard II: it
> > > starts to report middle-button push/release events with scrolling events
> > > between. A support for this keyboard was added in
> > > 24401f291dcc4f2c18b9e2f65763cbaadc7a1528 "HID: lenovo: Add support for
> > > ThinkPad TrackPoint Keyboard II" commit.
> >
> > I figured this out.
> >
> > This keyboard can emit REL_Y/REL_X events between of middle-button
> > events (if user was moving a cursor and press middle button without of
> > stopping this), so this algorithm does a false-positive detection and switches
> > the workaround off like for patched firmware:
> >
> > Event: time 1702140625.854777, type 2 (EV_REL), code 1 (REL_Y), value 2
> > Event: time 1702140625.854777, -------------- SYN_REPORT ------------
> > Event: time 1702140625.870769, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 1
> > Event: time 1702140625.870769, -------------- SYN_REPORT ------------
> > Event: time 1702140625.870771, type 2 (EV_REL), code 1 (REL_Y), value 2
> > Event: time 1702140625.870771, -------------- SYN_REPORT ------------
> > Event: time 1702140625.970780, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > Event: time 1702140625.970780, -------------- SYN_REPORT ------------
> > Event: time 1702140626.058800, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > Event: time 1702140626.058800, -------------- SYN_REPORT ------------
> > Event: time 1702140630.462974, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > Event: time 1702140630.462974, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 0
> > Event: time 1702140630.462974, -------------- SYN_REPORT ------------
>
> Maybe we should map the wheel HID reports to REL_Y/REL_X in
> lenovo_input_mapping_tpIIkbd() to allow libinput to do its wheel emulation job?
> I tried this but I am not familiar with HID drivers and had no success.
>
>
> >
> >
> > >
> > > There is an evtest output below:
> > >
> > > Without of commit:
> > >
> > > Middle-button click:
> > > Event: time 1702122290.593300, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 1
> > > Event: time 1702122290.593300, -------------- SYN_REPORT ------------
> > > Event: time 1702122290.593312, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 0
> > > Event: time 1702122290.593312, -------------- SYN_REPORT ------------
> > >
> > > Vertical scrolling:
> > > Event: time 1702122300.441627, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > > Event: time 1702122300.441627, -------------- SYN_REPORT ------------
> > > Event: time 1702122300.565663, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > > Event: time 1702122300.565663, -------------- SYN_REPORT ------------
> > >
> > > Horizontal scrolling:
> > > Event: time 1702122307.845969, type 2 (EV_REL), code 6 (REL_HWHEEL), value -1
> > > Event: time 1702122307.845969, -------------- SYN_REPORT ------------
> > > Event: time 1702122307.981954, type 2 (EV_REL), code 6 (REL_HWHEEL), value -1
> > > Event: time 1702122307.981954, -------------- SYN_REPORT ------------
> > >
> > >
> > >
> > > After commit:
> > >
> > > Middle-button click:
> > > Event: time 1702125091.290045, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125091.290045, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 1
> > > Event: time 1702125091.290045, -------------- SYN_REPORT ------------
> > > Event: time 1702125092.626118, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125092.626118, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 0
> > > Event: time 1702125092.626118, -------------- SYN_REPORT ------------
> > >
> > >
> > > Vscroll:
> > > Event: time 1702125286.653639, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125286.653639, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 1
> > > Event: time 1702125286.653639, -------------- SYN_REPORT ------------
> > > Event: time 1702125287.929689, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > > Event: time 1702125287.929689, -------------- SYN_REPORT ------------
> > > Event: time 1702125288.037688, type 2 (EV_REL), code 8 (REL_WHEEL), value -1
> > > Event: time 1702125288.037688, -------------- SYN_REPORT ------------
> > > Event: time 1702125290.481787, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125290.481787, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 0
> > > Event: time 1702125290.481787, -------------- SYN_REPORT ------------
> > >
> > > Hscroll:
> > > Event: time 1702125293.841920, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125293.841920, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 1
> > > Event: time 1702125293.841920, -------------- SYN_REPORT ------------
> > > Event: time 1702125294.761952, type 2 (EV_REL), code 6 (REL_HWHEEL), value -1
> > > Event: time 1702125294.761952, -------------- SYN_REPORT ------------
> > > Event: time 1702125294.893967, type 2 (EV_REL), code 6 (REL_HWHEEL), value -1
> > > Event: time 1702125294.893967, -------------- SYN_REPORT ------------
> > > Event: time 1702125296.134006, type 4 (EV_MSC), code 4 (MSC_SCAN), value ffa000fb
> > > Event: time 1702125296.134006, type 1 (EV_KEY), code 274 (BTN_MIDDLE), value 0
> > > Event: time 1702125296.134006, -------------- SYN_REPORT ------------
> >
> > --
> > Yauhen Kharuzhy
>
> --
> Yauhen Kharuzhy