The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 46f781e0d151844589dc2125c8cce3300546f92a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025102010-botch-underling-438f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 46f781e0d151844589dc2125c8cce3300546f92a Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires bentiss@kernel.org Date: Wed, 8 Oct 2025 16:06:58 +0200 Subject: [PATCH] HID: multitouch: fix sticky fingers
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
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index 513b8673ad8d..179dc316b4b5 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 @@ -1814,6 +1814,7 @@ 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); @@ -1836,7 +1837,7 @@ 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); }