* [PATCH 1/2] HID: multitouch: fix sticky fingers
2025-10-08 14:06 [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks Benjamin Tissoires
@ 2025-10-08 14:06 ` Benjamin Tissoires
2025-10-08 14:06 ` [PATCH 2/2] selftests/hid: add tests for missing release on the Dell Synaptics Benjamin Tissoires
2025-10-15 15:27 ` [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks Jiri Kosina
2 siblings, 0 replies; 4+ messages in thread
From: Benjamin Tissoires @ 2025-10-08 14:06 UTC (permalink / raw)
To: Jiri Kosina, Shuah Khan
Cc: Peter Hutterer, linux-input, linux-kernel, linux-kselftest,
Benjamin Tissoires, stable
The sticky fingers quirk (MT_QUIRK_STICKY_FINGERS) was only considering
the case when slots were not released during the last report.
This can be problematic if the firmware forgets to release a finger
while others are still present.
This was observed on the Synaptics DLL0945 touchpad found on the Dell
XPS 9310 and the Dell Inspiron 5406.
Fixes: 4f4001bc76fd ("HID: multitouch: fix rare Win 8 cases when the touch up event gets missing")
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
drivers/hid/hid-multitouch.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 2879e65cf303b1456311ac06115adda5a78a2600..e1a5c7f3a25132094ed643910337474025852b22 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -94,9 +94,8 @@ enum report_mode {
TOUCHPAD_REPORT_ALL = TOUCHPAD_REPORT_BUTTONS | TOUCHPAD_REPORT_CONTACTS,
};
-#define MT_IO_FLAGS_RUNNING 0
-#define MT_IO_FLAGS_ACTIVE_SLOTS 1
-#define MT_IO_FLAGS_PENDING_SLOTS 2
+#define MT_IO_SLOTS_MASK GENMASK(7, 0) /* reserve first 8 bits for slot tracking */
+#define MT_IO_FLAGS_RUNNING 32
static const bool mtrue = true; /* default for true */
static const bool mfalse; /* default for false */
@@ -172,7 +171,11 @@ struct mt_device {
struct timer_list release_timer; /* to release sticky fingers */
struct hid_haptic_device *haptic; /* haptic related configuration */
struct hid_device *hdev; /* hid_device we're attached to */
- unsigned long mt_io_flags; /* mt flags (MT_IO_FLAGS_*) */
+ unsigned long mt_io_flags; /* mt flags (MT_IO_FLAGS_RUNNING)
+ * first 8 bits are reserved for keeping the slot
+ * states, this is fine because we only support up
+ * to 250 slots (MT_MAX_MAXCONTACT)
+ */
__u8 inputmode_value; /* InputMode HID feature value */
__u8 maxcontacts;
bool is_buttonpad; /* is this device a button pad? */
@@ -986,6 +989,7 @@ static void mt_release_pending_palms(struct mt_device *td,
for_each_set_bit(slotnum, app->pending_palm_slots, td->maxcontacts) {
clear_bit(slotnum, app->pending_palm_slots);
+ clear_bit(slotnum, &td->mt_io_flags);
input_mt_slot(input, slotnum);
input_mt_report_slot_inactive(input);
@@ -1019,12 +1023,6 @@ static void mt_sync_frame(struct mt_device *td, struct mt_application *app,
app->left_button_state = 0;
if (td->is_haptic_touchpad)
hid_haptic_pressure_reset(td->haptic);
-
- if (test_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags))
- set_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags);
- else
- clear_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags);
- clear_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags);
}
static int mt_compute_timestamp(struct mt_application *app, __s32 value)
@@ -1202,7 +1200,9 @@ static int mt_process_slot(struct mt_device *td, struct input_dev *input,
input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
- set_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags);
+ set_bit(slotnum, &td->mt_io_flags);
+ } else {
+ clear_bit(slotnum, &td->mt_io_flags);
}
return 0;
@@ -1337,7 +1337,7 @@ static void mt_touch_report(struct hid_device *hid,
* defect.
*/
if (app->quirks & MT_QUIRK_STICKY_FINGERS) {
- if (test_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags))
+ if (td->mt_io_flags & MT_IO_SLOTS_MASK)
mod_timer(&td->release_timer,
jiffies + msecs_to_jiffies(100));
else
@@ -1813,6 +1813,7 @@ static void mt_release_contacts(struct hid_device *hid)
for (i = 0; i < mt->num_slots; i++) {
input_mt_slot(input_dev, i);
input_mt_report_slot_inactive(input_dev);
+ clear_bit(i, &td->mt_io_flags);
}
input_mt_sync_frame(input_dev);
input_sync(input_dev);
@@ -1835,7 +1836,7 @@ static void mt_expired_timeout(struct timer_list *t)
*/
if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
return;
- if (test_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags))
+ if (td->mt_io_flags & MT_IO_SLOTS_MASK)
mt_release_contacts(hdev);
clear_bit_unlock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
}
--
2.51.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] selftests/hid: add tests for missing release on the Dell Synaptics
2025-10-08 14:06 [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks Benjamin Tissoires
2025-10-08 14:06 ` [PATCH 1/2] HID: multitouch: fix sticky fingers Benjamin Tissoires
@ 2025-10-08 14:06 ` Benjamin Tissoires
2025-10-15 15:27 ` [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks Jiri Kosina
2 siblings, 0 replies; 4+ messages in thread
From: Benjamin Tissoires @ 2025-10-08 14:06 UTC (permalink / raw)
To: Jiri Kosina, Shuah Khan
Cc: Peter Hutterer, linux-input, linux-kernel, linux-kselftest,
Benjamin Tissoires
Add a simple test for the corner case not currently covered by the
sticky fingers quirk. Because it's a corner case test, we only test this
on a couple of devices, not on all of them because the value of adding
the same test over and over is rather moot.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
.../testing/selftests/hid/tests/test_multitouch.py | 55 ++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/tools/testing/selftests/hid/tests/test_multitouch.py b/tools/testing/selftests/hid/tests/test_multitouch.py
index 5d2ffa3d59777e3cd93d1d7aebabc2a6b7ecb42a..ece0ba8e7d34b75d42245e5936ecf804c46b0846 100644
--- a/tools/testing/selftests/hid/tests/test_multitouch.py
+++ b/tools/testing/selftests/hid/tests/test_multitouch.py
@@ -1752,6 +1752,52 @@ class TestWin8TSConfidence(BaseTest.TestWin8Multitouch):
assert evdev.slots[0][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == -1
+ @pytest.mark.skip_if_uhdev(
+ lambda uhdev: "Confidence" not in uhdev.fields,
+ "Device not compatible, missing Confidence usage",
+ )
+ def test_mt_confidence_bad_multi_release(self):
+ """Check for the sticky finger being properly detected.
+
+ We first inject 3 fingers, then release only the second.
+ After 100 ms, we should receive a generated event about the
+ 2 missing fingers being released.
+ """
+ uhdev = self.uhdev
+ evdev = uhdev.get_evdev()
+
+ # send 3 touches
+ t0 = Touch(1, 50, 10)
+ t1 = Touch(2, 150, 100)
+ t2 = Touch(3, 250, 200)
+ r = uhdev.event([t0, t1, t2])
+ events = uhdev.next_sync_events()
+ self.debug_reports(r, uhdev, events)
+
+ # release the second
+ t1.tipswitch = False
+ r = uhdev.event([t1])
+ events = uhdev.next_sync_events()
+ self.debug_reports(r, uhdev, events)
+
+ # only the second is released
+ assert evdev.slots[0][libevdev.EV_ABS.ABS_MT_TRACKING_ID] != -1
+ assert evdev.slots[1][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == -1
+ assert evdev.slots[2][libevdev.EV_ABS.ABS_MT_TRACKING_ID] != -1
+
+ # wait for the timer to kick in
+ time.sleep(0.2)
+
+ events = uhdev.next_sync_events()
+ self.debug_reports([], uhdev, events)
+
+ # now all 3 fingers are released
+ assert libevdev.InputEvent(libevdev.EV_KEY.BTN_TOUCH, 0) in events
+ assert evdev.slots[0][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == -1
+ assert evdev.slots[1][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == -1
+ assert evdev.slots[2][libevdev.EV_ABS.ABS_MT_TRACKING_ID] == -1
+
+
class TestElanXPS9360(BaseTest.TestWin8Multitouch):
def create_device(self):
return Digitizer(
@@ -2086,3 +2132,12 @@ class Testsynaptics_06cb_ce08(BaseTest.TestPTP):
input_info=(BusType.I2C, 0x06CB, 0xCE08),
rdesc="05 01 09 02 a1 01 85 02 09 01 a1 00 05 09 19 01 29 02 15 00 25 01 75 01 95 02 81 02 95 06 81 01 05 01 09 30 09 31 15 81 25 7f 75 08 95 02 81 06 c0 c0 05 01 09 02 a1 01 85 18 09 01 a1 00 05 09 19 01 29 03 46 00 00 15 00 25 01 75 01 95 03 81 02 95 05 81 01 05 01 09 30 09 31 15 81 25 7f 75 08 95 02 81 06 c0 c0 06 00 ff 09 02 a1 01 85 20 09 01 a1 00 09 03 15 00 26 ff 00 35 00 46 ff 00 75 08 95 05 81 02 c0 c0 05 0d 09 05 a1 01 85 03 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 f8 04 75 10 55 0e 65 11 09 30 35 00 46 24 04 95 01 81 02 46 30 02 26 a0 02 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 f8 04 75 10 55 0e 65 11 09 30 35 00 46 24 04 95 01 81 02 46 30 02 26 a0 02 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 f8 04 75 10 55 0e 65 11 09 30 35 00 46 24 04 95 01 81 02 46 30 02 26 a0 02 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 f8 04 75 10 55 0e 65 11 09 30 35 00 46 24 04 95 01 81 02 46 30 02 26 a0 02 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 f8 04 75 10 55 0e 65 11 09 30 35 00 46 24 04 95 01 81 02 46 30 02 26 a0 02 09 31 81 02 c0 05 0d 55 0c 66 01 10 47 ff ff 00 00 27 ff ff 00 00 75 10 95 01 09 56 81 02 09 54 25 7f 95 01 75 08 81 02 05 09 09 01 25 01 75 01 95 01 81 02 95 07 81 03 05 0d 85 08 09 55 09 59 75 04 95 02 25 0f b1 02 85 0d 09 60 75 01 95 01 15 00 25 01 b1 02 95 07 b1 03 85 07 06 00 ff 09 c5 15 00 26 ff 00 75 08 96 00 01 b1 02 c0 05 0d 09 0e a1 01 85 04 09 22 a1 02 09 52 15 00 25 0a 75 08 95 01 b1 02 c0 09 22 a1 00 85 06 09 57 09 58 75 01 95 02 25 01 b1 02 95 06 b1 03 c0 c0 06 00 ff 09 01 a1 01 85 09 09 02 15 00 26 ff 00 75 08 95 14 91 02 85 0a 09 03 15 00 26 ff 00 75 08 95 14 91 02 85 0b 09 04 15 00 26 ff 00 75 08 95 45 81 02 85 0c 09 05 15 00 26 ff 00 75 08 95 45 81 02 85 0f 09 06 15 00 26 ff 00 75 08 95 03 b1 02 85 0e 09 07 15 00 26 ff 00 75 08 95 01 b1 02 c0",
)
+
+class Testsynaptics_06cb_ce26(TestWin8TSConfidence):
+ def create_device(self):
+ return PTP(
+ "uhid test synaptics_06cb_ce26",
+ max_contacts=5,
+ input_info=(BusType.I2C, 0x06CB, 0xCE26),
+ rdesc="05 01 09 02 a1 01 85 02 09 01 a1 00 05 09 19 01 29 02 15 00 25 01 75 01 95 02 81 02 95 06 81 01 05 01 09 30 09 31 15 81 25 7f 75 08 95 02 81 06 c0 c0 05 0d 09 05 a1 01 85 03 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 45 05 75 10 55 0e 65 11 09 30 35 00 46 64 04 95 01 81 02 46 a2 02 26 29 03 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 45 05 75 10 55 0e 65 11 09 30 35 00 46 64 04 95 01 81 02 46 a2 02 26 29 03 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 45 05 75 10 55 0e 65 11 09 30 35 00 46 64 04 95 01 81 02 46 a2 02 26 29 03 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 45 05 75 10 55 0e 65 11 09 30 35 00 46 64 04 95 01 81 02 46 a2 02 26 29 03 09 31 81 02 c0 05 0d 09 22 a1 02 15 00 25 01 09 47 09 42 95 02 75 01 81 02 95 01 75 03 25 05 09 51 81 02 75 01 95 03 81 03 05 01 15 00 26 45 05 75 10 55 0e 65 11 09 30 35 00 46 64 04 95 01 81 02 46 a2 02 26 29 03 09 31 81 02 c0 05 0d 55 0c 66 01 10 47 ff ff 00 00 27 ff ff 00 00 75 10 95 01 09 56 81 02 09 54 25 7f 95 01 75 08 81 02 05 09 09 01 25 01 75 01 95 01 81 02 95 07 81 03 05 0d 85 08 09 55 09 59 75 04 95 02 25 0f b1 02 85 0d 09 60 75 01 95 01 15 00 25 01 b1 02 95 07 b1 03 85 07 06 00 ff 09 c5 15 00 26 ff 00 75 08 96 00 01 b1 02 c0 05 0d 09 0e a1 01 85 04 09 22 a1 02 09 52 15 00 25 0a 75 08 95 01 b1 02 c0 09 22 a1 00 85 06 09 57 09 58 75 01 95 02 25 01 b1 02 95 06 b1 03 c0 c0 06 00 ff 09 01 a1 01 85 09 09 02 15 00 26 ff 00 75 08 95 14 91 02 85 0a 09 03 15 00 26 ff 00 75 08 95 14 91 02 85 0b 09 04 15 00 26 ff 00 75 08 95 3d 81 02 85 0c 09 05 15 00 26 ff 00 75 08 95 3d 81 02 85 0f 09 06 15 00 26 ff 00 75 08 95 03 b1 02 85 0e 09 07 15 00 26 ff 00 75 08 95 01 b1 02 c0",
+ )
--
2.51.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks
2025-10-08 14:06 [PATCH 0/2] HID: multitouch: fix sticky-fingers quirks Benjamin Tissoires
2025-10-08 14:06 ` [PATCH 1/2] HID: multitouch: fix sticky fingers Benjamin Tissoires
2025-10-08 14:06 ` [PATCH 2/2] selftests/hid: add tests for missing release on the Dell Synaptics Benjamin Tissoires
@ 2025-10-15 15:27 ` Jiri Kosina
2 siblings, 0 replies; 4+ messages in thread
From: Jiri Kosina @ 2025-10-15 15:27 UTC (permalink / raw)
To: Benjamin Tissoires
Cc: Shuah Khan, Peter Hutterer, linux-input, linux-kernel,
linux-kselftest, stable
On Wed, 8 Oct 2025, Benjamin Tissoires wrote:
> According to Peter, we've had for a very long time an issue on some
> mutltiouch touchpads where the fingers were stuck in a scrolling mode,
> or 3 fingers gesture mode. I was unable to debug it because it was
> rather hard to reproduce.
>
> Recently, some people raised the issue again on libinput, and this time
> added a recording of the actual bug.
>
> It turns out that the sticky finger quirk that was introduced back in
> 2017 was only checking the last report, and that those missing releases
> also happen when moving from 3 to 1 finger (only 1 is released instead
> of 2).
>
> This solution seems to me to be the most sensible, because we could also
> add the NSMU quirk to win8 multitouch touchpads, but this would involve
> a lot more computations at each report for rather annoying corner cases.
>
> Link: https://gitlab.freedesktop.org/libinput/libinput/-/issues/1194
> Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
> ---
> Benjamin Tissoires (2):
> HID: multitouch: fix sticky fingers
> selftests/hid: add tests for missing release on the Dell Synaptics
>
> drivers/hid/hid-multitouch.c | 27 ++++++-----
> .../testing/selftests/hid/tests/test_multitouch.py | 55 ++++++++++++++++++++++
> 2 files changed, 69 insertions(+), 13 deletions(-)
Now queued in for-6.18/upstream-fixes. Thanks,
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 4+ messages in thread