[PATCH libinput] touchpad: require at least 3 events before enabling trackpoint palm detection

[Peter Hutterer]

On Wed, Sep 07, 2016 at 10:22:22AM +1000, Peter Hutterer wrote:
> Some trackpoints, notably the one on the Lenovo T460s have a tendency to send
> the odd event even when they're not actually used. Trackpoint events trigger
> palm detection (see 0210f1fee193) and thus effectively disable the touchpad,
> causing the touchpad to appear nonresponsive.
> 
> Fix this by requiring at least 3 events from a trackpoint before palm
> detection is enabled. For normal use it's hard enough to trigger a single
> event anyway so this should not affect the normal use-case.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>

follow-up: this is actually this bug here:
https://bugzilla.redhat.com/show_bug.cgi?id=1364850
after looking at the wrong thing for a while I found that comment 3 shows
that single event from event5 (the trackpoint node).

Cheers,
   Peter

> ---
>  src/evdev-mt-touchpad.c |  9 ++++++++-
>  src/evdev-mt-touchpad.h |  1 +
>  test/trackpoint.c       | 26 ++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
> index 65b0abf..8f7dbf0 100644
> --- a/src/evdev-mt-touchpad.c
> +++ b/src/evdev-mt-touchpad.c
> @@ -1302,6 +1302,7 @@ tp_trackpoint_timeout(uint64_t now, void *data)
>  
>  	tp_tap_resume(tp, now);
>  	tp->palm.trackpoint_active = false;
> +	tp->palm.trackpoint_event_count = 0;
>  }
>  
>  static void
> @@ -1314,6 +1315,13 @@ tp_trackpoint_event(uint64_t time, struct libinput_event *event, void *data)
>  	if (event->type == LIBINPUT_EVENT_POINTER_BUTTON)
>  		return;
>  
> +	tp->palm.trackpoint_last_event_time = time;
> +	tp->palm.trackpoint_event_count++;
> +
> +	/* Require at least three events before enabling palm detection */
> +	if (tp->palm.trackpoint_event_count < 3)
> +		return;
> +
>  	if (!tp->palm.trackpoint_active) {
>  		tp_edge_scroll_stop_events(tp, time);
>  		tp_gesture_cancel(tp, time);
> @@ -1321,7 +1329,6 @@ tp_trackpoint_event(uint64_t time, struct libinput_event *event, void *data)
>  		tp->palm.trackpoint_active = true;
>  	}
>  
> -	tp->palm.trackpoint_last_event_time = time;
>  	libinput_timer_set(&tp->palm.trackpoint_timer,
>  			   time + DEFAULT_TRACKPOINT_ACTIVITY_TIMEOUT);
>  }
> diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
> index 8a8d2db..c2edb83 100644
> --- a/src/evdev-mt-touchpad.h
> +++ b/src/evdev-mt-touchpad.h
> @@ -337,6 +337,7 @@ struct tp_dispatch {
>  		struct libinput_event_listener trackpoint_listener;
>  		struct libinput_timer trackpoint_timer;
>  		uint64_t trackpoint_last_event_time;
> +		uint32_t trackpoint_event_count;
>  		bool monitor_trackpoint;
>  	} palm;
>  
> diff --git a/test/trackpoint.c b/test/trackpoint.c
> index b92b994..e9ba027 100644
> --- a/test/trackpoint.c
> +++ b/test/trackpoint.c
> @@ -349,6 +349,31 @@ START_TEST(trackpoint_palmdetect_resume_touch)
>  }
>  END_TEST
>  
> +START_TEST(trackpoint_palmdetect_require_min_events)
> +{
> +	struct litest_device *trackpoint = litest_current_device();
> +	struct litest_device *touchpad;
> +	struct libinput *li = trackpoint->libinput;
> +
> +	touchpad = litest_add_device(li, LITEST_SYNAPTICS_I2C);
> +	litest_drain_events(li);
> +
> +	/* A single event does not trigger palm detection */
> +	litest_event(trackpoint, EV_REL, REL_X, 1);
> +	litest_event(trackpoint, EV_REL, REL_Y, 1);
> +	litest_event(trackpoint, EV_SYN, SYN_REPORT, 0);
> +	libinput_dispatch(li);
> +	litest_drain_events(li);
> +
> +	litest_touch_down(touchpad, 0, 30, 30);
> +	litest_touch_move_to(touchpad, 0, 30, 30, 80, 80, 10, 1);
> +	litest_touch_up(touchpad, 0);
> +	litest_assert_only_typed_events(li, LIBINPUT_EVENT_POINTER_MOTION);
> +
> +	litest_delete_device(touchpad);
> +}
> +END_TEST
> +
>  void
>  litest_setup_tests_trackpoint(void)
>  {
> @@ -362,4 +387,5 @@ litest_setup_tests_trackpoint(void)
>  
>  	litest_add("trackpoint:palmdetect", trackpoint_palmdetect, LITEST_POINTINGSTICK, LITEST_ANY);
>  	litest_add("trackpoint:palmdetect", trackpoint_palmdetect_resume_touch, LITEST_POINTINGSTICK, LITEST_ANY);
> +	litest_add("trackpoint:palmdetect", trackpoint_palmdetect_require_min_events, LITEST_POINTINGSTICK, LITEST_ANY);
>  }
> -- 
> 2.7.4
> 
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