HID: multitouch: enable palm rejection if device implements confidence usage

The usage Confidence is mandary to Windows Precision Touchpad devices. The
appearance of this usage is checked in hidinput_connect but the quirk
MT_QUIRK_VALID_IS_CONFIDENCE is not applied to device accordingly.
Apply this quirk and also remove quirk MT_QUIRK_ALWAYS_VALID to enable palm
rejection for the WIN 8 touchpad devices which have implemented usage
Confidence in its input reports.

Tested on Dell XPS 13 laptop.

Signed-off-by: Allen Hung <allen_hung@dell.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 3d664d01305e..351ddd297792 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -486,6 +486,11 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                         mt_store_field(usage, td, hi);
                         return 1;
                 case HID_DG_CONFIDENCE:
+                        if (cls->name == MT_CLS_WIN_8 &&
+                                field->application == HID_DG_TOUCHPAD) {
+                                cls->quirks &= ~MT_QUIRK_ALWAYS_VALID;
+                                cls->quirks |= MT_QUIRK_VALID_IS_CONFIDENCE;
+                        }
                         mt_store_field(usage, td, hi);
                         return 1;
                 case HID_DG_TIPSWITCH: