HID: MacBookPro15,4 reporting 05ac:0277 — add WELLSPRINGT2_J223_ALT for keyboard backlight and trackpad

[c0deAbra]

Summary

On this MacBookPro15,4 (board Mac-53FDB3D8DB8CA971, i.e. J223) the internal
keyboard/trackpad enumerates as 05ac:0277 instead of 0x027f. That product
id appears in no kernel table, so hid-generic claims all five interfaces:

• no keyboard backlight LED is registered at all, and
• the trackpad degrades to a plain 3-button relative mouse — EV=17 ABS=0 REL=3 PROP=0,
  i.e. not even a scroll axis — so libinput has nothing to build two-finger scroll
  or gestures from.

The hardware is otherwise an ordinary J223. Adding the id as WELLSPRINGT2_J223_ALT,
mirroring the existing J680_ALT (0x0278) precedent where Apple likewise ships an
alternate product id for one board, makes both work fully.

Environment

Model	MacBookPro15,4 / Mac-53FDB3D8DB8CA971
Kernel	7.1.8-arch1-...-t2 (Arch linux-t2 7.1.8.arch1-3)
Patch series	linux-t2-patches @ 79ed04627b (KVER=7.1.4)

usb 5-5: New USB device found, idVendor=05ac, idProduct=0277, bcdDevice= 8.96
usb 5-5: Product: Apple Internal Keyboard / Trackpad

Interface layout is the usual T2 one: iface 0/3/4 vendor collections, iface 1
the keyboard (vendor usage ff00.000f present), iface 2 the HID_TYPE_USBMOUSE
trackpad.

Evidence that it really is a J223

Keyboard backlight. Interface 1 answers the 0xBF backlight config feature
report with a valid structure:

$ HIDIOCGFEATURE(0xBF) on the iface-1 hidraw node
bf 01 00 00 20 00 00 02
   ^^ version=1  ^^^^^ on_min=32  ^^^^^ on_max=512

Binding hid-apple to interface 1 with the J223 quirks (via the HID bus new_id
interface, plus APPLE_BACKLIGHT_CTL) registers apple::kbd_backlight with
max_brightness = 512, and it works — including the Touch Bar's
XF86KbdBrightnessUp/Down keys.

Trackpad. Building hid-magicmouse with 0x0277 added alongside J223
(same geometry: X -6046..6536, Y -164..7439) turns it into a real clickpad:

before:  EV=17  ABS=0                 REL=3  PROP=0
after:   EV=1b  ABS=67f800001000003   REL=0  PROP=5   (POINTER|BUTTONPAD)

with the full multitouch stack — ABS_MT_SLOT, ABS_MT_POSITION_X/Y,
ABS_MT_TRACKING_ID, ABS_MT_PRESSURE, ABS_MT_TOUCH_MAJOR/MINOR,
ABS_MT_ORIENTATION. Pointing, two-finger scroll and gestures all behave
correctly, so the J223 geometry is right for this unit.

Note on APPLE_BACKLIGHT_CTL

The current J223 entry in hid-apple has no APPLE_BACKLIGHT_CTL, yet this
unit answers the backlight reports and drives the LED correctly. The proposed
entry includes the quirk; the plain J223 entry may deserve it too, but I have
no 0x027f machine to confirm that on.

Why new_id is not enough

hid-apple is quirk-driven, so the keyboard side can be handled at runtime with
new_id. hid-magicmouse cannot: it selects trackpad geometry and the
multitouch-enable feature report with switch (id->product), and new_id only
supplies driver_data. An unlisted id falls through every case, so the id has to
be compiled in — hence this request rather than a local workaround.

Patch

Against the tree with 4001/4003/4004/4005 applied. I have been running it
(as a DKMS build of hid-magicmouse plus new_id for hid-apple) with both
devices fully working.

--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@
 #define USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223		0x027f
+#define USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT	0x0277
 #define USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K		0x0280

--- a/drivers/hid/hid-apple.c
+++ b/drivers/hid/hid-apple.c
@@
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223),
 		.driver_data = APPLE_HAS_FN | APPLE_ISO_TILDE_QUIRK | APPLE_DISABLE_FKEYS |
 				APPLE_IGNORE_MOUSE },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT),
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL | APPLE_ISO_TILDE_QUIRK |
+				APPLE_DISABLE_FKEYS | APPLE_IGNORE_MOUSE },

--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -195,6 +195,15 @@
 #define J223_TP_RES_Y \
 	((J223_TP_MAX_Y - J223_TP_MIN_Y) / (J223_TP_DIMENSION_Y / 100))
 
+#define J223_ALT_TP_DIMENSION_X J223_TP_DIMENSION_X
+#define J223_ALT_TP_MIN_X J223_TP_MIN_X
+#define J223_ALT_TP_MAX_X J223_TP_MAX_X
+#define J223_ALT_TP_RES_X J223_TP_RES_X
+#define J223_ALT_TP_DIMENSION_Y J223_TP_DIMENSION_Y
+#define J223_ALT_TP_MIN_Y J223_TP_MIN_Y
+#define J223_ALT_TP_MAX_Y J223_TP_MAX_Y
+#define J223_ALT_TP_RES_Y J223_TP_RES_Y
+
 #define J230K_TP_DIMENSION_X (float)12100
 #define J230K_TP_MIN_X -5318
 #define J230K_TP_MAX_X 5787
@@ -1169,6 +1178,7 @@
 	T2_TOUCHPAD_ENTRY(J213),
 	T2_TOUCHPAD_ENTRY(J214K),
 	T2_TOUCHPAD_ENTRY(J223),
+	T2_TOUCHPAD_ENTRY(J223_ALT),
 	T2_TOUCHPAD_ENTRY(J230K),
 	T2_TOUCHPAD_ENTRY(J152F),
 };
@@ -1387,6 +1397,7 @@
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J213:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J214K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223:
+	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J152F:
 		feature_size = sizeof(feature_mt_trackpad2_usb);
@@ -1498,6 +1509,7 @@
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J213:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J214K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223:
+	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J152F:
 		if (hdev->type != HID_TYPE_USBMOUSE)
@@ -1531,6 +1543,7 @@
 		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J213:
 		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J214K:
 		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223:
+		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT:
 		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K:
 		case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J152F:
 			msc->input_ops.raw_event = magicmouse_raw_event_t2;
@@ -1607,6 +1620,7 @@
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J213:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J214K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223:
+	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K:
 	case USB_DEVICE_ID_APPLE_WELLSPRINGT2_J152F:
 		report = hid_register_report(hdev, HID_INPUT_REPORT,
@@ -1733,6 +1747,8 @@
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE,
 		USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223), .driver_data = 0 },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE,
+		USB_DEVICE_ID_APPLE_WELLSPRINGT2_J223_ALT), .driver_data = 0 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE,
 		USB_DEVICE_ID_APPLE_WELLSPRINGT2_J230K), .driver_data = 0 },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE,
 		USB_DEVICE_ID_APPLE_WELLSPRINGT2_J152F), .driver_data = 0 },

Happy to turn this into a PR in the series' numbering scheme if that is preferred,
and to run any test you want on the hardware.