linux-kernel - [PATCH v5] hid/hid-multitouch: Keep latency normal on deactivate for reactivation gesture

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Message-ID: <20260108161139.32681-1-wse@tuxedocomputers.com>
Date: Thu,  8 Jan 2026 17:09:54 +0100
From: Werner Sembach <wse@...edocomputers.com>
To: Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>
Cc: Werner Sembach <wse@...edocomputers.com>,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v5] hid/hid-multitouch: Keep latency normal on deactivate for reactivation gesture

Uniwill devices have a built in gesture in the touchpad to de- and
reactivate it by double taping the upper left corner. This gesture stops
working when latency is set to high, so this patch keeps the latency on
normal.

Cc: stable@...r.kernel.org
Signed-off-by: Werner Sembach <wse@...edocomputers.com>
---
V1->V2: Use a quirk to narrow down the devices this is applied to.
V2->V3: Fix this patch breaking touchpads on some devices.
        Add another device ID.
V3->V4: Readd quirks formerly applied to the devices via the default class.
V4->V5: Fix whitespace error.

 drivers/hid/hid-multitouch.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 179dc316b4b51..62e7036806549 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -76,6 +76,7 @@ MODULE_LICENSE("GPL");
 #define MT_QUIRK_DISABLE_WAKEUP		BIT(21)
 #define MT_QUIRK_ORIENTATION_INVERT	BIT(22)
 #define MT_QUIRK_APPLE_TOUCHBAR		BIT(23)
+#define MT_QUIRK_KEEP_LATENCY_ON_CLOSE	BIT(24)
 
 #define MT_INPUTMODE_TOUCHSCREEN	0x02
 #define MT_INPUTMODE_TOUCHPAD		0x03
@@ -211,6 +212,7 @@ static void mt_post_parse(struct mt_device *td, struct mt_application *app);
 #define MT_CLS_WIN_8_DISABLE_WAKEUP		0x0016
 #define MT_CLS_WIN_8_NO_STICKY_FINGERS		0x0017
 #define MT_CLS_WIN_8_FORCE_MULTI_INPUT_NSMU	0x0018
+#define MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE	0x0019
 
 /* vendor specific classes */
 #define MT_CLS_3M				0x0101
@@ -330,6 +332,15 @@ static const struct mt_class mt_classes[] = {
 			MT_QUIRK_CONTACT_CNT_ACCURATE |
 			MT_QUIRK_WIN8_PTP_BUTTONS,
 		.export_all_inputs = true },
+	{ .name = MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE,
+		.quirks = MT_QUIRK_ALWAYS_VALID |
+			MT_QUIRK_IGNORE_DUPLICATES |
+			MT_QUIRK_HOVERING |
+			MT_QUIRK_CONTACT_CNT_ACCURATE |
+			MT_QUIRK_STICKY_FINGERS |
+			MT_QUIRK_WIN8_PTP_BUTTONS |
+			MT_QUIRK_KEEP_LATENCY_ON_CLOSE,
+		.export_all_inputs = true },
 
 	/*
 	 * vendor specific classes
@@ -830,7 +841,8 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			if ((cls->name == MT_CLS_WIN_8 ||
 			     cls->name == MT_CLS_WIN_8_FORCE_MULTI_INPUT ||
 			     cls->name == MT_CLS_WIN_8_FORCE_MULTI_INPUT_NSMU ||
-			     cls->name == MT_CLS_WIN_8_DISABLE_WAKEUP) &&
+			     cls->name == MT_CLS_WIN_8_DISABLE_WAKEUP ||
+			     cls->name == MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE) &&
 				(field->application == HID_DG_TOUCHPAD ||
 				 field->application == HID_DG_TOUCHSCREEN))
 				app->quirks |= MT_QUIRK_CONFIDENCE;
@@ -1709,7 +1721,8 @@ static int mt_input_configured(struct hid_device *hdev, struct hid_input *hi)
 	int ret;
 
 	if (td->is_haptic_touchpad && (td->mtclass.name == MT_CLS_WIN_8 ||
-	    td->mtclass.name == MT_CLS_WIN_8_FORCE_MULTI_INPUT)) {
+	    td->mtclass.name == MT_CLS_WIN_8_FORCE_MULTI_INPUT ||
+	    td->mtclass.name == MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE)) {
 		if (hid_haptic_input_configured(hdev, td->haptic, hi) == 0)
 			td->is_haptic_touchpad = false;
 	} else {
@@ -1998,7 +2011,12 @@ static void mt_on_hid_hw_open(struct hid_device *hdev)
 
 static void mt_on_hid_hw_close(struct hid_device *hdev)
 {
-	mt_set_modes(hdev, HID_LATENCY_HIGH, TOUCHPAD_REPORT_NONE);
+	struct mt_device *td = hid_get_drvdata(hdev);
+
+	if (td->mtclass.quirks & MT_QUIRK_KEEP_LATENCY_ON_CLOSE)
+		mt_set_modes(hdev, HID_LATENCY_NORMAL, TOUCHPAD_REPORT_NONE);
+	else
+		mt_set_modes(hdev, HID_LATENCY_HIGH, TOUCHPAD_REPORT_NONE);
 }
 
 /*
@@ -2375,6 +2393,14 @@ static const struct hid_device_id mt_devices[] = {
 		MT_USB_DEVICE(USB_VENDOR_ID_UNITEC,
 			USB_DEVICE_ID_UNITEC_USB_TOUCH_0A19) },
 
+	/* Uniwill touchpads */
+	{ .driver_data = MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE,
+		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
+			USB_VENDOR_ID_PIXART, 0x0255) },
+	{ .driver_data = MT_CLS_WIN_8_KEEP_LATENCY_ON_CLOSE,
+		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
+			USB_VENDOR_ID_PIXART, 0x0274) },
+
 	/* VTL panels */
 	{ .driver_data = MT_CLS_VTL,
 		MT_USB_DEVICE(USB_VENDOR_ID_VTL,
-- 
2.43.0