HID: multitouch: detect serial protocol

Microsoft's documentation about multitouch protocols tells that
if a device presents one touch per report, then it should be treated
as a serial protocol.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index a61ba42e1bff..6fb46d70f39d 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -81,6 +81,9 @@ struct mt_device {
         __u8 num_received;      /* how many contacts we received */
         __u8 num_expected;      /* expected last contact index */
         __u8 maxcontacts;
+        __u8 touches_by_report; /* how many touches are present in one report:
+                                * 1 means we should use a serial protocol
+                                * > 1 means hybrid (multitouch) protocol */
         bool curvalid;          /* is the current contact valid? */
         struct mt_slot *slots;
 };
@@ -365,6 +368,7 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         input_mt_init_slots(hi->input, td->maxcontacts);
                         td->last_slot_field = usage->hid;
                         td->last_field_index = field->index;
+                        td->touches_by_report++;
                         return 1;
                 case HID_DG_WIDTH:
                         hid_map_usage(hi, usage, bit, max,
@@ -670,6 +674,15 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
         if (ret)
                 goto fail;
 
+        if (!id && td->touches_by_report == 1) {
+                /* the device has been sent by hid-generic */
+                mtclass = &td->mtclass;
+                mtclass->quirks |= MT_QUIRK_ALWAYS_VALID;
+                mtclass->quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
+                mtclass->quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
+                mtclass->quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
+        }
+
         td->slots = kzalloc(td->maxcontacts * sizeof(struct mt_slot),
                                 GFP_KERNEL);
         if (!td->slots) {