Input: synaptics - reset the ABS_X/Y fuzz after initializing MT axes

input_mt_init_slots() resets the ABS_X/Y fuzz to 0 and expects the driver
to call input_mt_report_pointer_emulation(). That is based on the MT
position bits which are already defuzzed - hence a fuzz of 0.

In the case of synaptics semi-mt devices, we report the ABS_X/Y axes
manually.  This results in the MT position being defuzzed but the
single-touch emulation missing that defuzzing.

Work around this by re-initializing the ABS_X/Y axes after the MT axis to
get the same fuzz value back.

https://bugs.freedesktop.org/show_bug.cgi?id=104533

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/synaptics.c

@@ -1280,6 +1280,16 @@ static void set_input_params(struct psmouse *psmouse,
 				    INPUT_MT_POINTER |
 				    (cr48_profile_sensor ?
 					INPUT_MT_TRACK : INPUT_MT_SEMI_MT));
+
+		/*
+		 * For semi-mt devices we send ABS_X/Y ourselves instead of
+		 * input_mt_report_pointer_emulation. But
+		 * input_mt_init_slots() resets the fuzz to 0, leading to a
+		 * filtered ABS_MT_POSITION_X but an unfiltered ABS_X
+		 * position. Let's re-initialize ABS_X/Y here.
+		 */
+		if (!cr48_profile_sensor)
+			set_abs_position_params(dev, &priv->info, ABS_X, ABS_Y);
 	}
 
 	if (SYN_CAP_PALMDETECT(info->capabilities))