touchpad: ignore the tap motion threshold if fingers > slots

Do so on the synaptics serial touchpads at least, they're known to cause
cursor jumps when the third finger is down. Not detecting a tap move means
three-finger taps get more reliable on these touchpads.

This change affects gestures who now effectively have to wait for the tap
timeout to happen. It's a trade-off.

https://bugs.freedesktop.org/show_bug.cgi?id=101435
https://bugzilla.redhat.com/show_bug.cgi?id=1455443

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

diff --git a/src/evdev-mt-touchpad-tap.c b/src/evdev-mt-touchpad-tap.c
index 5a237fe..3ab3316 100644 (file)
--- a/src/evdev-mt-touchpad-tap.c
+++ b/src/evdev-mt-touchpad-tap.c
@@ -768,6 +768,18 @@ tp_tap_exceeds_motion_threshold(struct tp_dispatch *tp,
        struct phys_coords mm =
                tp_phys_delta(tp, device_delta(t->point, t->tap.initial));
 
+       /* if we have more fingers down than slots, we know that synaptics
+        * touchpads are likely to give us pointer jumps.
+        * This triggers the movement threshold, making three-finger taps
+        * less reliable (#101435)
+        */
+       if (tp->device->model_flags & EVDEV_MODEL_SYNAPTICS_SERIAL_TOUCHPAD &&
+           (tp->nfingers_down > 2 || tp->old_nfingers_down > 2) &&
+           (tp->nfingers_down > tp->num_slots ||
+            tp->old_nfingers_down > tp->num_slots)) {
+               return false;
+       }
+
        return length_in_mm(mm) > DEFAULT_TAP_MOVE_THRESHOLD;
 }
 

diff --git a/test/test-touchpad-tap.c b/test/test-touchpad-tap.c
index 1e9a8c9..bdfab81 100644 (file)
--- a/test/test-touchpad-tap.c
+++ b/test/test-touchpad-tap.c
@@ -1691,6 +1691,59 @@ START_TEST(touchpad_3fg_tap_btntool_inverted)
 }
 END_TEST
 
+START_TEST(touchpad_3fg_tap_btntool_pointerjump)
+{
+       struct litest_device *dev = litest_current_device();
+       struct libinput *li = dev->libinput;
+       enum libinput_config_tap_button_map map = _i; /* ranged test */
+       unsigned int button = 0;
+
+       if (libevdev_get_abs_maximum(dev->evdev,
+                                    ABS_MT_SLOT) > 2)
+               return;
+
+       litest_enable_tap(dev->libinput_device);
+       litest_set_tap_map(dev->libinput_device, map);
+
+       switch (map) {
+       case LIBINPUT_CONFIG_TAP_MAP_LRM:
+               button = BTN_MIDDLE;
+               break;
+       case LIBINPUT_CONFIG_TAP_MAP_LMR:
+               button = BTN_RIGHT;
+               break;
+       default:
+               litest_abort_msg("Invalid map range %d", map);
+       }
+
+       litest_drain_events(li);
+
+       litest_touch_down(dev, 0, 50, 50);
+       litest_touch_down(dev, 1, 70, 50);
+       litest_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, 1);
+       litest_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, 0);
+       litest_event(dev, EV_SYN, SYN_REPORT, 0);
+       /* Pointer jump should be ignored */
+       litest_touch_move_to(dev, 0, 50, 50, 20, 20, 0, 0);
+       libinput_dispatch(li);
+       litest_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, 0);
+       litest_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, 1);
+       litest_event(dev, EV_SYN, SYN_REPORT, 0);
+       litest_touch_up(dev, 1);
+       litest_touch_up(dev, 0);
+
+       libinput_dispatch(li);
+
+       litest_assert_button_event(li, button,
+                                  LIBINPUT_BUTTON_STATE_PRESSED);
+       litest_timeout_tap();
+       litest_assert_button_event(li, button,
+                                  LIBINPUT_BUTTON_STATE_RELEASED);
+
+       litest_assert_empty_queue(li);
+}
+END_TEST
+
 START_TEST(touchpad_4fg_tap)
 {
        struct litest_device *dev = litest_current_device();
@@ -2362,6 +2415,7 @@ litest_setup_tests_touchpad_tap(void)
        litest_add_ranged("tap-3fg:3fg", touchpad_3fg_tap, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH, &tap_map_range);
        litest_add("tap-3fg:3fg", touchpad_3fg_tap_tap_again, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
        litest_add("tap-3fg:3fg", touchpad_3fg_tap_quickrelease, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH);
+       litest_add_for_device("tap-3fg:3fg", touchpad_3fg_tap_btntool_pointerjump, LITEST_SYNAPTICS_TOPBUTTONPAD);
        litest_add("tap-4fg:4fg", touchpad_4fg_tap, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH|LITEST_SEMI_MT);
        litest_add("tap-4fg:4fg", touchpad_4fg_tap_quickrelease, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH|LITEST_SEMI_MT);
        litest_add("tap-5fg:5fg", touchpad_5fg_tap, LITEST_TOUCHPAD, LITEST_SINGLE_TOUCH|LITEST_SEMI_MT);