HID: multitouch: change for touch height/width

Quoting  from Jonathan Clarke in previous thread(2017/01/24):

"This division by 2 was added along with the touch width/height fields 6 years
ago so that those fields 'match the visual scale of the touch' for a specific
device (3M PCT)" "The scaling is also discarding information about touch size
(1 bit for each of width/height) which is useful for any application that wants
to know about it."

Jonathan mentioned just what I thought in a new project recently.  It dosen't
make sense to discard 1 bit width/height in general case according to the spec
in multi-touch-protocol.txt so I would like to make a slight change here.

A quirk MT_QUIRK_TOUCH_SIZE_SCALING was added to service devices like 3M PCT
with a special visual scale and the division by 2 only take effect with devices
like that.

[jkosina@suse.cz: reformat changelog]
Signed-off-by: HungNien Chen <hn.chen@weidahitech.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-multitouch.c

@@ -69,6 +69,7 @@ MODULE_LICENSE("GPL");
 #define MT_QUIRK_CONTACT_CNT_ACCURATE	(1 << 12)
 #define MT_QUIRK_FORCE_GET_FEATURE	(1 << 13)
 #define MT_QUIRK_FIX_CONST_CONTACT_ID	(1 << 14)
+#define MT_QUIRK_TOUCH_SIZE_SCALING	(1 << 15)
 
 #define MT_INPUTMODE_TOUCHSCREEN	0x02
 #define MT_INPUTMODE_TOUCHPAD		0x03
@@ -222,7 +223,8 @@ static struct mt_class mt_classes[] = {
 	 */
 	{ .name = MT_CLS_3M,
 		.quirks = MT_QUIRK_VALID_IS_CONFIDENCE |
-			MT_QUIRK_SLOT_IS_CONTACTID,
+			MT_QUIRK_SLOT_IS_CONTACTID |
+			MT_QUIRK_TOUCH_SIZE_SCALING,
 		.sn_move = 2048,
 		.sn_width = 128,
 		.sn_height = 128,
@@ -658,9 +660,17 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 		if (active) {
 			/* this finger is in proximity of the sensor */
 			int wide = (s->w > s->h);
-			/* divided by two to match visual scale of touch */
-			int major = max(s->w, s->h) >> 1;
-			int minor = min(s->w, s->h) >> 1;
+			int major = max(s->w, s->h);
+			int minor = min(s->w, s->h);
+
+			/*
+			 * divided by two to match visual scale of touch
+			 * for devices with this quirk
+			 */
+			if (td->mtclass.quirks & MT_QUIRK_TOUCH_SIZE_SCALING) {
+				major = major >> 1;
+				minor = minor >> 1;
+			}
 
 			input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
 			input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);