[PATCH 1/2] HID: wacom: Correct behavior when processing some confidence == false touches

[PATCH 1/2] HID: wacom: Correct behavior when processing some confidence == false touches

[Gerecke, Jason]

From: Jason Gerecke <jason.gerecke@wacom.com>

There appear to be a few different ways that Wacom devices can deal with
confidence:

  1. If the device looses confidence in a touch, it will first clear
     the tipswitch flag in one report, and then clear the confidence
     flag in a second report. This behavior is used by e.g. DTH-2452.

  2. If the device looses confidence in a touch, it will clear both
     the tipswitch and confidence flags within the same report. This
     behavior is used by some AES devices.

  3. If the device looses confidence in a touch, it will clear *only*
     the confidence bit. The tipswitch bit will remain set so long as
     the touch is tracked. This behavior may be used in future devices.

The driver does not currently handle situation 3 properly. Touches that
loose confidence will remain "in prox" and essentially frozen in place
until the tipswitch bit is finally cleared. Not only does this result
in userspace seeing a stuck touch, but it also prevents pen arbitration
from working properly (the pen won't send events until all touches are
up, but we don't currently process events from non-confident touches).

This commit centralizes the checking of the confidence bit in the
wacom_wac_finger_slot() function and has 'prox' depend on it. In the
case where situation 3 is encountered, the treat the touch as though
it was removed, allowing both userspace and the pen arbitration to
act normally.

Signed-off-by: Tatsunosuke Tobita <tatsunosuke.tobita@wacom.com>
Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Fixes: 7fb0413baa7f ("HID: wacom: Use "Confidence" flag to prevent reporting invalid contacts")
Cc: stable@vger.kernel.org
---
 drivers/hid/wacom_wac.c | 32 ++++----------------------------
 1 file changed, 4 insertions(+), 28 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 471db78dbbf0..8289ce763704 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2649,8 +2649,8 @@ static void wacom_wac_finger_slot(struct wacom_wac *wacom_wac,
 {
 	struct hid_data *hid_data = &wacom_wac->hid_data;
 	bool mt = wacom_wac->features.touch_max > 1;
-	bool prox = hid_data->tipswitch &&
-		    report_touch_events(wacom_wac);
+	bool touch_down = hid_data->tipswitch && hid_data->confidence;
+	bool prox = touch_down && report_touch_events(wacom_wac);
 
 	if (touch_is_muted(wacom_wac)) {
 		if (!wacom_wac->shared->touch_down)
@@ -2700,24 +2700,6 @@ static void wacom_wac_finger_slot(struct wacom_wac *wacom_wac,
 	}
 }
 
-static bool wacom_wac_slot_is_active(struct input_dev *dev, int key)
-{
-	struct input_mt *mt = dev->mt;
-	struct input_mt_slot *s;
-
-	if (!mt)
-		return false;
-
-	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
-		if (s->key == key &&
-			input_mt_get_value(s, ABS_MT_TRACKING_ID) >= 0) {
-			return true;
-		}
-	}
-
-	return false;
-}
-
 static void wacom_wac_finger_event(struct hid_device *hdev,
 		struct hid_field *field, struct hid_usage *usage, __s32 value)
 {
@@ -2768,14 +2750,8 @@ static void wacom_wac_finger_event(struct hid_device *hdev,
 	}
 
 	if (usage->usage_index + 1 == field->report_count) {
-		if (equivalent_usage == wacom_wac->hid_data.last_slot_field) {
-			bool touch_removed = wacom_wac_slot_is_active(wacom_wac->touch_input,
-				wacom_wac->hid_data.id) && !wacom_wac->hid_data.tipswitch;
-
-			if (wacom_wac->hid_data.confidence || touch_removed) {
-				wacom_wac_finger_slot(wacom_wac, wacom_wac->touch_input);
-			}
-		}
+		if (equivalent_usage == wacom_wac->hid_data.last_slot_field)
+			wacom_wac_finger_slot(wacom_wac, wacom_wac->touch_input);
 	}
 }
 
-- 
2.43.0

[PATCH 2/2] HID: wacom: Add additional tests of confidence behavior

[Gerecke, Jason]

From: Jason Gerecke <jason.gerecke@wacom.com>

Test for proper driver behavior when the touch confidence bit is set
or cleared. Test the three flavors of touch confidence loss (tipswitch
cleared before confidence, tipswitch and confidence cleared at the same
time, and tipswitch only cleared when touch is actually removed). Also
test two flavors of touch confidence gain (confidence added to a touch
that was "never" confident, and confidence added to a touch that was
previously confident).

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
---
 .../selftests/hid/tests/test_wacom_generic.py | 278 +++++++++++++++++-
 1 file changed, 277 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/hid/tests/test_wacom_generic.py b/tools/testing/selftests/hid/tests/test_wacom_generic.py
index f92fe8e02c1b..a7ee54e5090b 100644
--- a/tools/testing/selftests/hid/tests/test_wacom_generic.py
+++ b/tools/testing/selftests/hid/tests/test_wacom_generic.py
@@ -27,6 +27,7 @@ from .descriptors_wacom import (
 )
 
 import attr
+from collections import namedtuple
 from enum import Enum
 from hidtools.hut import HUT
 from hidtools.hid import HidUnit
@@ -862,6 +863,8 @@ class TestPTHX60_Pen(TestOpaqueCTLTablet):
 
 
 class TestDTH2452Tablet(test_multitouch.BaseTest.TestMultitouch, TouchTabletTest):
+    ContactIds = namedtuple("ContactIds", "contact_id, tracking_id, slot_num")
+
     def create_device(self):
         return test_multitouch.Digitizer(
             "DTH 2452",
@@ -869,6 +872,57 @@ class TestDTH2452Tablet(test_multitouch.BaseTest.TestMultitouch, TouchTabletTest
             input_info=(0x3, 0x056A, 0x0383),
         )
 
+    def make_contact(self, contact_id=0, t=0):
+        """
+        Make a single touch contact that can move over time.
+
+        Creates a touch object that has a well-known position in space that
+        does not overlap with other contacts. The value of `t` may be
+        incremented over time to move the point along a linear path.
+        """
+        x = 50 + 10 * contact_id + t
+        y = 100 + 100 * contact_id + t
+        return test_multitouch.Touch(contact_id, x, y)
+
+    def make_contacts(self, n, t=0):
+        """
+        Make multiple touch contacts that can move over time.
+
+        Returns a list of `n` touch objects that are positioned at well-known
+        locations. The value of `t` may be incremented over time to move the
+        points along a linear path.
+        """
+        return [ self.make_contact(id, t) for id in range(0, n) ]
+
+    def assert_contact(self, uhdev, evdev, contact_ids, t=0):
+        """
+        Assert properties of a contact generated by make_contact.
+        """
+        contact_id = contact_ids.contact_id
+        tracking_id = contact_ids.tracking_id
+        slot_num = contact_ids.slot_num
+
+        x = 50 + 10 * contact_id + t
+        y = 100 + 100 * contact_id + t
+
+        # If the data isn't supposed to be stored in any slots, there is
+        # nothing we can check for in the evdev stream.
+        if slot_num is None:
+            assert tracking_id == -1
+            return
+
+        assert evdev.slots[slot_num][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == tracking_id
+        if tracking_id != -1:
+            assert evdev.slots[slot_num][libevdev.EV_ABS.ABS_MT_POSITION_X] == x
+            assert evdev.slots[slot_num][libevdev.EV_ABS.ABS_MT_POSITION_Y] == y
+
+    def assert_contacts(self, uhdev, evdev, data, t=0):
+        """
+        Assert properties of a list of contacts generated by make_contacts.
+        """
+        for contact_ids in data:
+            self.assert_contact(uhdev, evdev, contact_ids, t)
+
     def test_contact_id_0(self):
         """
         Bring a finger in contact with the tablet, then hold it down and remove it.
@@ -919,4 +973,226 @@ class TestDTH2452Tablet(test_multitouch.BaseTest.TestMultitouch, TouchTabletTest
 
         slot = self.get_slot(uhdev, t0, 0)
 
-        assert not events
\ No newline at end of file
+        assert not events
+
+    def test_confidence_multitouch(self):
+        """
+        Bring multiple fingers in contact with the tablet, some with the
+        confidence bit set, and some without.
+
+        Ensure that all confident touches are reported and that all non-
+        confident touches are ignored.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        touches = self.make_contacts(5)
+        touches[0].confidence = False
+        touches[2].confidence = False
+        touches[4].confidence = False
+
+        r = uhdev.event(touches)
+        events = uhdev.next_sync_events()
+        self.debug_reports(r, uhdev, events)
+
+        assert libevdev.InputEvent(libevdev.EV_KEY.BTN_TOUCH, 1) in events
+
+        self.assert_contacts(uhdev, evdev,
+            [ self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = None),
+              self.ContactIds(contact_id = 1, tracking_id = 0, slot_num = 0),
+              self.ContactIds(contact_id = 2, tracking_id = -1, slot_num = None),
+              self.ContactIds(contact_id = 3, tracking_id = 1, slot_num = 1),
+              self.ContactIds(contact_id = 4, tracking_id = -1, slot_num = None) ])
+
+    def confidence_change_assert_playback(self, uhdev, evdev, timeline):
+        """
+        Assert proper behavior of contacts that move and change tipswitch /
+        confidence status over time.
+
+        Given a `timeline` list of touch states to iterate over, verify
+        that the contacts move and are reported as up/down as expected
+        by the state of the tipswitch and confidence bits.
+        """
+        t = 0
+
+        for state in timeline:
+            touches = self.make_contacts(len(state), t)
+
+            for item in zip(touches, state):
+                item[0].tipswitch = item[1][1]
+                item[0].confidence = item[1][2]
+
+            r = uhdev.event(touches)
+            events = uhdev.next_sync_events()
+            self.debug_reports(r, uhdev, events)
+
+            ids = [ x[0] for x in state ]
+            self.assert_contacts(uhdev, evdev, ids, t)
+
+            t += 1
+
+    def test_confidence_loss_a(self):
+        """
+        Transition a confident contact to a non-confident contact by
+        first clearing the tipswitch.
+
+        Ensure that the driver reports the transitioned contact as
+        being removed and that other contacts continue to report
+        normally. This mode of confidence loss is used by the
+        DTH-2452.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        self.confidence_change_assert_playback(uhdev, evdev, [
+            # t=0: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # Both fingers confidently in contact
+            [(self.ContactIds(contact_id = 0, tracking_id = 0, slot_num = 0), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=1: Contact 0 == !Down + confident; Contact 1 == Down + confident
+            # First finger looses confidence and clears only the tipswitch flag
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=2: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=3: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)]
+        ])
+
+    def test_confidence_loss_b(self):
+        """
+        Transition a confident contact to a non-confident contact by
+        cleraing both tipswitch and confidence bits simultaneously.
+
+        Ensure that the driver reports the transitioned contact as
+        being removed and that other contacts continue to report
+        normally. This mode of confidence loss is used by some
+        AES devices.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        self.confidence_change_assert_playback(uhdev, evdev, [
+            # t=0: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # Both fingers confidently in contact
+            [(self.ContactIds(contact_id = 0, tracking_id = 0, slot_num = 0), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=1: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger looses confidence and has both flags cleared simultaneously
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=2: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=3: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)]
+        ])
+
+    def test_confidence_loss_c(self):
+        """
+        Transition a confident contact to a non-confident contact by
+        clearing only the confidence bit.
+
+        Ensure that the driver reports the transitioned contact as
+        being removed and that other contacts continue to report
+        normally.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        self.confidence_change_assert_playback(uhdev, evdev, [
+            # t=0: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # Both fingers confidently in contact
+            [(self.ContactIds(contact_id = 0, tracking_id = 0, slot_num = 0), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=1: Contact 0 == Down + !confident; Contact 1 == Down + confident
+            # First finger looses confidence and clears only the confidence flag
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), True, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=2: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=3: Contact 0 == !Down + !confident; Contact 1 == Down + confident
+            # First finger has lost confidence and has both flags cleared
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)]
+        ])
+
+    def test_confidence_gain_a(self):
+        """
+        Transition a contact that was always non-confident to confident.
+
+        Ensure that the confident contact is reported normally.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        self.confidence_change_assert_playback(uhdev, evdev, [
+            # t=0: Contact 0 == Down + !confident; Contact 1 == Down + confident
+            # Only second finger is confidently in contact
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = None), True, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 0, slot_num = 0), True, True)],
+
+            # t=1: Contact 0 == Down + !confident; Contact 1 == Down + confident
+            # First finger gains confidence
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = None), True, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 0, slot_num = 0), True, True)],
+
+            # t=2: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # First finger remains confident
+            [(self.ContactIds(contact_id = 0, tracking_id = 1, slot_num = 1), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 0, slot_num = 0), True, True)],
+
+            # t=3: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # First finger remains confident
+            [(self.ContactIds(contact_id = 0, tracking_id = 1, slot_num = 1), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 0, slot_num = 0), True, True)]
+        ])
+
+    def test_confidence_gain_b(self):
+        """
+        Transition a contact from non-confident to confident.
+
+        Ensure that the confident contact is reported normally.
+        """
+        uhdev = self.uhdev
+        evdev = uhdev.get_evdev()
+
+        self.confidence_change_assert_playback(uhdev, evdev, [
+            # t=0: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # First and second finger confidently in contact
+            [(self.ContactIds(contact_id = 0, tracking_id = 0, slot_num = 0), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=1: Contact 0 == Down + !confident; Contact 1 == Down + confident
+            # Firtst finger looses confidence
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), True, False),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=2: Contact 0 == Down + confident; Contact 1 == Down + confident
+            # First finger gains confidence
+            [(self.ContactIds(contact_id = 0, tracking_id = 2, slot_num = 0), True, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)],
+
+            # t=3: Contact 0 == !Down + confident; Contact 1 == Down + confident
+            # First finger goes up
+            [(self.ContactIds(contact_id = 0, tracking_id = -1, slot_num = 0), False, True),
+             (self.ContactIds(contact_id = 1, tracking_id = 1, slot_num = 1), True, True)]
+        ])
-- 
2.43.0

Re: [PATCH 1/2] HID: wacom: Correct behavior when processing some confidence == false touches

[Jiri Kosina]

Jason,

both patches applied to hid.git#for-6.8/wacom.

Thanks,

-- 
Jiri Kosina
SUSE Labs