On Oct 20 2025, bentiss@kernel.org wrote:
From: Benjamin Tissoires bentiss@kernel.org
commit 46f781e0d151844589dc2125c8cce3300546f92a upstream.
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 Signed-off-by: Jiri Kosina jkosina@suse.com Signed-off-by: Benjamin Tissoires bentiss@kernel.org
Greg,
This backport also applies cleanly up to 5.10. Though I'm not sure we want to go that far in the history TBH.
Can you also take this version and apply it to 6.1+? (or do you want me to send individual rebases for each tree?)
Cheers, Benjamin
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 5c424010bc02..0667a24576fc 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -83,9 +83,8 @@ enum latency_mode { HID_LATENCY_HIGH = 1, }; -#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 */ @@ -160,7 +159,11 @@ struct mt_device { struct mt_class mtclass; /* our mt device class */ struct timer_list release_timer; /* to release sticky fingers */ 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)*/@@ -941,6 +944,7 @@ 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); @@ -972,12 +976,6 @@ static void mt_sync_frame(struct mt_device *td, struct mt_application *app, app->num_received = 0; app->left_button_state = 0;
- 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) @@ -1152,7 +1150,9 @@ 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; @@ -1287,7 +1287,7 @@ 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));@@ -1734,6 +1734,7 @@ 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);@@ -1756,7 +1757,7 @@ 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