[PATCH 2/2] HID: magicmouse: high-resolution scroll threshold

From: José Expósito
Date: Wed Jul 07 2021 - 11:59:04 EST


In order to avoid triggering involuntary high-resolution scroll events
due to tiny touch movement deltas, add a movement threshold.

The value chosen for the threshold, about 1.5 ~ 2 mm, is similar to the
threshold used on touchpads by libinput (see libinput
evdev-mt-touchpad-gestures.c) to try to keep the scroll experience
consistent.

Signed-off-by: José Expósito <jose.exposito89@xxxxxxxxx>
---
drivers/hid/hid-magicmouse.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index e95f46dab4ad..686788ebf3e1 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -71,6 +71,7 @@ MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state fie
/* Number of high-resolution events for each low-resolution detent. */
#define SCROLL_HR_STEPS 10
#define SCROLL_HR_MULT (120 / SCROLL_HR_STEPS)
+#define SCROLL_HR_THRESHOLD 90 /* units */
#define SCROLL_ACCEL_DEFAULT 7

/* Touch surface information. Dimension is in hundredths of a mm, min and max
@@ -132,6 +133,8 @@ struct magicmouse_sc {
short scroll_x_hr;
short scroll_y_hr;
u8 size;
+ bool scroll_x_active;
+ bool scroll_y_active;
} touches[16];
int tracking_ids[16];

@@ -265,6 +268,8 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
msc->touches[id].scroll_y = y;
msc->touches[id].scroll_x_hr = x;
msc->touches[id].scroll_y_hr = y;
+ msc->touches[id].scroll_x_active = false;
+ msc->touches[id].scroll_y_active = false;

/* Reset acceleration after half a second. */
if (scroll_acceleration && time_before(now,
@@ -292,8 +297,16 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
input_report_rel(input, REL_WHEEL, step_y);
}

+ if (!msc->touches[id].scroll_x_active &&
+ abs(step_x_hr) > SCROLL_HR_THRESHOLD) {
+ msc->touches[id].scroll_x_active = true;
+ msc->touches[id].scroll_x_hr = x;
+ step_x_hr = 0;
+ }
+
step_x_hr /= step_hr;
- if (step_x_hr != 0) {
+ if (step_x_hr != 0 &&
+ msc->touches[id].scroll_x_active) {
msc->touches[id].scroll_x_hr -= step_x_hr *
step_hr;
input_report_rel(input,
@@ -301,8 +314,16 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
-step_x_hr * SCROLL_HR_MULT);
}

+ if (!msc->touches[id].scroll_y_active &&
+ abs(step_y_hr) > SCROLL_HR_THRESHOLD) {
+ msc->touches[id].scroll_y_active = true;
+ msc->touches[id].scroll_y_hr = y;
+ step_y_hr = 0;
+ }
+
step_y_hr /= step_hr;
- if (step_y_hr != 0) {
+ if (step_y_hr != 0 &&
+ msc->touches[id].scroll_y_active) {
msc->touches[id].scroll_y_hr -= step_y_hr *
step_hr;
input_report_rel(input,
--
2.25.1