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touchpad: reset the motion history during/after a slots->nfake crossover

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Whenever we cross from N slots to at least one fake finger, reset the motion
history and skip the next event too. Especially on serial Synaptics touchpads,
the first touch update after a two-slot → TRIPLETAP is garbage, as is the one
from TRIPLETAP → two slots.

Example sequence reproduce on a T440s:

E: 4.488757 0003 003a 0084      # EV_ABS / ABS_MT_PRESSURE      84
E: 4.488757 0003 002f 0001      # EV_ABS / ABS_MT_SLOT          1
E: 4.488757 0003 0039 0433      # EV_ABS / ABS_MT_TRACKING_ID   433
E: 4.488757 0003 0035 2500      # EV_ABS / ABS_MT_POSITION_X    2500
E: 4.488757 0003 0036 3064      # EV_ABS / ABS_MT_POSITION_Y    3064
E: 4.488757 0003 003a 0060      # EV_ABS / ABS_MT_PRESSURE      60
E: 4.488757 0003 0018 0084      # EV_ABS / ABS_PRESSURE         84
E: 4.488757 0001 0145 0000      # EV_KEY / BTN_TOOL_FINGER      0
E: 4.488757 0001 014e 0001      # EV_KEY / BTN_TOOL_TRIPLETAP   1
E: 4.488757 0000 0000 0000      # ------------ SYN_REPORT (0) ----------
E: 4.508506 0003 002f 0000      # EV_ABS / ABS_MT_SLOT          0
E: 4.508506 0003 0036 2982      # EV_ABS / ABS_MT_POSITION_Y    2982
E: 4.508506 0003 003a 0086      # EV_ABS / ABS_MT_PRESSURE      86
E: 4.508506 0003 002f 0001      # EV_ABS / ABS_MT_SLOT          1
E: 4.508506 0003 0035 3464      # EV_ABS / ABS_MT_POSITION_X    3464
E: 4.508506 0003 0036 2716      # EV_ABS / ABS_MT_POSITION_Y    2716
E: 4.508506 0003 0001 2982      # EV_ABS / ABS_Y                2982
E: 4.508506 0003 0018 0086      # EV_ABS / ABS_PRESSURE         86
E: 4.508506 0000 0000 0000      # ------------ SYN_REPORT (0) ----------

subsequent events then hover around the 3464 mark, but that initial jump is
enough to cause a massive cursor jump.

https://bugs.freedesktop.org/show_bug.cgi?id=91352

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Hallelujah-expressed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Peter Hutterer 2015-07-20 13:10:29 +10:00
parent d4ceb671b9
commit a87d51f9d7
2 changed files with 36 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

29
src/evdev-mt-touchpad.c
View file

@ -760,6 +760,24 @@ tp_unhover_touches(struct tp_dispatch *tp, uint64_t time)
}
static inline bool
tp_need_motion_history_reset(struct tp_dispatch *tp)
{
/* semi-mt finger postions may "jump" when nfingers changes */
if (tp->semi_mt && tp->nfingers_down != tp->old_nfingers_down)
return true;
/* if we're transitioning between slots and fake touches in either
* direction, we may get a coordinate jump
*/
if (tp->nfingers_down != tp->old_nfingers_down &&
(tp->nfingers_down > tp->num_slots ||
tp->old_nfingers_down > tp->num_slots))
return true;
return false;
}
static void
tp_process_state(struct tp_dispatch *tp, uint64_t time)
{
@ -767,16 +785,23 @@ tp_process_state(struct tp_dispatch *tp, uint64_t time)
struct tp_touch *first = tp_get_touch(tp, 0);
unsigned int i;
bool restart_filter = false;
bool want_motion_reset;
tp_process_fake_touches(tp, time);
tp_unhover_touches(tp, time);
want_motion_reset = tp_need_motion_history_reset(tp);
for (i = 0; i < tp->ntouches; i++) {
t = tp_get_touch(tp, i);
/* semi-mt finger postions may "jump" when nfingers changes */
if (tp->semi_mt && tp->nfingers_down != tp->old_nfingers_down)
if (want_motion_reset) {
tp_motion_history_reset(t);
t->quirks.reset_motion_history = true;
} else if (t->quirks.reset_motion_history) {
tp_motion_history_reset(t);
t->quirks.reset_motion_history = false;
}
if (i >= tp->num_slots && t->state != TOUCH_NONE) {
t->point = first->point;

9
src/evdev-mt-touchpad.h
View file

@ -147,6 +147,15 @@ struct tp_touch {
int distance; /* distance == 0 means touch */
int pressure;
struct {
/* A quirk mostly used on Synaptics touchpads. In a
transition to/from fake touches > num_slots, the current
event data is likely garbage and the subsequent event
is likely too. This marker tells us to reset the motion
history again -> this effectively swallows any motion */
bool reset_motion_history;
} quirks;
struct {
struct device_coords samples[TOUCHPAD_HISTORY_LENGTH];
unsigned int index;