# \[PATCH v3 3/5\] HID: multitouch: take cls-\>maxcontacts into account for Apple Touch Bar even without a HID\_DG\_CONTACTMAX field

- From: Aditya Garg \<hidden\>
- Date: 2025-05-27 16:54:47 
- List: linux-input
- Page: https://ratatoskr.run/linux-input/2025/05/3070653
- Thread: https://ratatoskr.run/linux-input/2025/05/3070650/t.md

```text
From: Kerem Karabay <redacted>

In Apple Touch Bar, the HID_DG_CONTACTMAX is not present, but the maximum
contact count is still greater than the default. Add quirks for the same.

Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Kerem Karabay <redacted>
Co-developed-by: Aditya Garg <redacted>
Signed-off-by: Aditya Garg <redacted>
---
 drivers/hid/hid-multitouch.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 99ecf6c8e..f71500d1f 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -1335,6 +1335,13 @@ static int mt_touch_input_configured(struct hid_device *hdev,
 	struct input_dev *input = hi->input;
 	int ret;
 
+	/*
+	 * HID_DG_CONTACTMAX field is not present on Apple Touch Bars,
+	 * but the maximum contact count is greater than the default.
+	 */
+	if (cls->quirks & MT_QUIRK_APPLE_TOUCHBAR && cls->maxcontacts)
+		td->maxcontacts = cls->maxcontacts;
+
 	if (!td->maxcontacts)
 		td->maxcontacts = MT_DEFAULT_MAXCONTACT;
 
-- 
2.43.0

```