[PATCH libinput] touchpad: cap the edge palm detection zones at 8mm

[Peter Hutterer]

The main purpose of the edge zone is to detect palms in the area where we
cannot assume a full finger size and thus cannot use any other palm detection
mechanism. 8mm should be large enough that a finger should be detected based
on other properties (size, pressure, ...).

https://bugs.freedesktop.org/show_bug.cgi?id=103330

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/evdev-mt-touchpad.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index 81a56a05..8bb0661b 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -2646,8 +2646,8 @@ tp_init_palmdetect_edge(struct tp_dispatch *tp,
 	if (width < 70.0)
 		return;
 
-	/* palm edges are 8% of the width on each side */
-	mm.x = width * 0.08;
+	/* palm edges are 8% of the width on each side up to a max of 7mm */
+	mm.x = min(8, width * 0.08);
 	edges = evdev_device_mm_to_units(device, &mm);
 	tp->palm.left_edge = edges.x;
 
-- 
2.13.6