[PATCH v4 13/14] HID: hid-multitouch: fix Win 8 protocol

[Benjamin Tissoires]

The Win 8 protocol specify the fact that each valid touch must be reported
within a frame until it is released.
We can therefore use the always_valid quirk and dismiss reports when we see
duplicate contacts ID.

We recognize Win8 certified devices from their vendor feature 0xff0000c5
where Microsoft put a signed blob in the report to check if the device
passed the certification.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
---
 drivers/hid/hid-multitouch.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 5f26b2f..efae60c 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -295,6 +295,18 @@ static void mt_feature_mapping(struct hid_device *hdev,
 			td->maxcontacts = td->mtclass.maxcontacts;
 
 		break;
+	case 0xff0000c5:
+		if (field->report_count == 256 && field->report_size == 8) {
+			/* Win 8 devices need special quirks */
+			__s32 *quirks = &td->mtclass.quirks;
+			*quirks |= MT_QUIRK_ALWAYS_VALID;
+			*quirks |= MT_QUIRK_IGNORE_DUPLICATES;
+			*quirks |= MT_QUIRK_HOVERING;
+			*quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
+			*quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
+			*quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
+		}
+		break;
 	}
 }
 
-- 
1.8.0

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