HID: multitouch: require Finger field to mark Win8 reports as MT

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

Cc: stable@vger.kernel.org
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 9d9f3e1bd5f418bb61ccb50eabf6e0b1711b2bb2..55dcb8536286b62cb54561c76128a6aca0a95db4 100644 (file)
--- 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;
+                               }
+                       }
                }
        }