[PATCH v2 1/4] HID: multitouch: require Finger field to mark Win8 reports as MT

[Ahelenia Ziemiańska]

This effectively changes collection_is_mt from
  contact ID in report->field
to
  (device is Win8 => collection is finger) && contact ID in report->field

Some devices erroneously report Pen for fingers,
and Win8 stylus-on-touchscreen devices report contact ID,
but mark the accompanying touchscreen device's collection correctly

Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@xxxxxxxxxxxxxxxxxx>
---
 drivers/hid/hid-multitouch.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 8429ebe7097e..8580ace596c2 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -604,9 +604,13 @@ static struct mt_report_data *mt_allocate_report_data(struct mt_device *td,
 		if (!(HID_MAIN_ITEM_VARIABLE & field->flags))
 			continue;
 
-		for (n = 0; n < field->report_count; n++) {
-			if (field->usage[n].hid == HID_DG_CONTACTID)
-				rdata->is_mt_collection = true;
+		if (field->logical == HID_DG_FINGER || td->hdev->group != HID_GROUP_MULTITOUCH_WIN_8) {
+			for (n = 0; n < field->report_count; n++) {
+				if (field->usage[n].hid == HID_DG_CONTACTID) {
+					rdata->is_mt_collection = true;
+					break;
+				}
+			}
 		}
 	}
 
-- 
2.20.1

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