[PATCH] HID: elecom: Add support for ELECOM M-XT4DRBK (018E)
From: Berke Durak
Date: Mon Sep 07 2026 - 14:50:02 EST
The 2025 revision of the left-handed EX-G wireless trackball
(M-XT4DRBK-G) reports USB ID 056e:018e instead of 056e:00fd. Its report
descriptor declares an 8-bit button field (Report Count 8) but only five
usages (Usage Maximum 5), so the sixth (Fn) button ends up as a
duplicate of button 5 and is unusable.
The report descriptor has the same layout as the M-XT3DRBK 018C
(button usage maximum at offset 16, button report count at 22, button
report size at 24, padding report size at 30), so reuse that fixup.
Rename the existing M_XT4DRBK define to M_XT4DRBK_00FD to match the
convention used for the other EX-G revisions.
Tested on a Raspberry Pi 5 with the same fixup in an
out-of-tree module on 6.12 (6.12.96+rpt-rpi-2712);
all six buttons are reported after the fix, and they
work (tested with xev as well).
Report descriptor as sent by the device, pre-fix (056e:018e,
215 bytes):
05 01 09 02 A1 01 09 01 A1 00 85 01 05 09 19 01
29 05 15 00 25 01 95 08 75 01 81 02 95 01 75 00
81 01 05 01 09 30 09 31 16 00 80 26 FF 7F 75 10
95 02 81 06 C0 A1 00 05 01 09 38 15 81 25 7F 75
08 95 01 81 06 C0 A1 00 05 0C 0A 38 02 95 01 75
08 15 81 25 7F 81 06 C0 C0 06 01 FF 09 00 A1 01
85 02 09 00 15 00 26 FF 00 75 08 95 07 81 02 C0
05 0C 09 01 A1 01 85 05 15 00 26 3C 02 19 00 2A
3C 02 75 10 95 01 81 00 C0 05 01 09 80 A1 01 85
03 19 81 29 83 15 00 25 01 95 03 75 01 81 02 95
01 75 05 81 01 C0 06 BC FF 09 88 A1 01 85 04 95
01 75 08 15 00 26 FF 00 19 00 2A FF 00 81 00 C0
06 02 FF 09 02 A1 01 85 06 09 02 15 00 26 FF 00
75 08 95 07 B1 02 C0
Assisted-by: LLM
Signed-off-by: Berke Durak <berke.durak@xxxxxxxxx>
---
diff -urN a/drivers/hid/hid-elecom.c b/drivers/hid/hid-elecom.c
--- a/drivers/hid/hid-elecom.c
+++ b/drivers/hid/hid-elecom.c
@@ -79,7 +79,7 @@
case USB_DEVICE_ID_ELECOM_M_XT3URBK_00FB:
case USB_DEVICE_ID_ELECOM_M_XT3URBK_018F:
case USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC:
- case USB_DEVICE_ID_ELECOM_M_XT4DRBK:
+ case USB_DEVICE_ID_ELECOM_M_XT4DRBK_00FD:
/*
* Report descriptor format:
* 12: button bit count
@@ -104,6 +104,7 @@
mouse_button_fixup(hdev, rdesc, *rsize, 12, 30, 14, 20, 8);
break;
case USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C:
+ case USB_DEVICE_ID_ELECOM_M_XT4DRBK_018E:
/*
* Report descriptor format:
* 22: button bit count
@@ -148,7 +149,8 @@
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK_018F) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C) },
- { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },
+ { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK_00FD) },
+ { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK_018E) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT2DRBK) },
diff -urN a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -477,7 +477,8 @@
#define USB_DEVICE_ID_ELECOM_M_XT3URBK_018F 0x018f
#define USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC 0x00fc
#define USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C 0x018c
-#define USB_DEVICE_ID_ELECOM_M_XT4DRBK 0x00fd
+#define USB_DEVICE_ID_ELECOM_M_XT4DRBK_00FD 0x00fd
+#define USB_DEVICE_ID_ELECOM_M_XT4DRBK_018E 0x018e
#define USB_DEVICE_ID_ELECOM_M_DT1URBK 0x00fe
#define USB_DEVICE_ID_ELECOM_M_DT1DRBK 0x00ff
#define USB_DEVICE_ID_ELECOM_M_DT2DRBK 0x018d
diff -urN a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
--- a/drivers/hid/hid-quirks.c
+++ b/drivers/hid/hid-quirks.c
@@ -431,7 +431,8 @@
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK_018F) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_00FC) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK_018C) },
- { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },
+ { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK_00FD) },
+ { HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK_018E) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT2DRBK) },