touchpad: use pressure values for touch is-down decision

Don't rely on BTN_TOUCH for "finger down", the value for that is hardcoded in
the kernel and not always suitable. Some devices need a different value to
avoid reacting to accidental touches or hovering fingers.

Implement a basic Schmitt trigger, same as we have in the synaptics driver. We
also take the default values from there but these will likely see some
updates.

A special case is when we have more fingers down than slots. Since we can't
detect the pressure on fake fingers (we only get a bit for 'is down') we
assume that *all* fingers are down with sufficient pressure. It's too much of
a niche case to have this work any other way.

This patch drops the handling of ABS_DISTANCE because it's simply not needed
anymore.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/test/litest-device-synaptics-hover.c b/test/litest-device-synaptics-hover.c
index 8439f10..9c0c7bd 100644
--- a/test/litest-device-synaptics-hover.c
+++ b/test/litest-device-synaptics-hover.c
@@ -60,9 +60,23 @@ static struct input_event move[] = {
 	{ .type = -1, .code = -1 },
 };
 
+static int
+get_axis_default(struct litest_device *d, unsigned int evcode, int32_t *value)
+{
+	switch (evcode) {
+	case ABS_PRESSURE:
+	case ABS_MT_PRESSURE:
+		*value = 30;
+		return 0;
+	}
+	return 1;
+}
+
 static struct litest_device_interface interface = {
 	.touch_down_events = down,
 	.touch_move_events = move,
+
+	.get_axis_default = get_axis_default,
 };
 
 static struct input_id input_id = {