[PATCH v5 4/10] HID: multitouch: support getting the contact ID from HID_DG_TRANSDUCER_INDEX fields

[Aditya Garg]

From: Kerem Karabay <kek...@gmail.com>

This is needed to support Apple Touch Bars, where the contact ID is
contained in fields with the HID_DG_TRANSDUCER_INDEX usage.

Signed-off-by: Kerem Karabay <kek...@gmail.com>
Signed-off-by: Aditya Garg <gargadity...@live.com>
---
 drivers/hid/hid-multitouch.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 56fc78841..3e92789ed 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -635,7 +635,9 @@ static struct mt_report_data 
*mt_allocate_report_data(struct mt_device *td,
 
                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) {
+                               unsigned int hid = field->usage[n].hid;
+
+                               if (hid == HID_DG_CONTACTID || hid == 
HID_DG_TRANSDUCER_INDEX) {
                                        rdata->is_mt_collection = true;
                                        break;
                                }
@@ -814,6 +816,7 @@ static int mt_touch_input_mapping(struct hid_device *hdev, 
struct hid_input *hi,
                        MT_STORE_FIELD(tip_state);
                        return 1;
                case HID_DG_CONTACTID:
+               case HID_DG_TRANSDUCER_INDEX:
                        MT_STORE_FIELD(contactid);
                        app->touches_by_report++;
                        return 1;
-- 
2.43.0