We must not reassign those axes or we will break backwards-compat. Add a
small note for that so we don't accidentally some day reuse these.

Signed-off-by: David Herrmann <redacted>
---
 include/uapi/linux/input.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h
index a372627..da1125e 100644
--- a/include/uapi/linux/input.h
+++ b/include/uapi/linux/input.h

@@ -816,6 +816,10 @@ struct input_keymap_entry {

 #define ABS_MISC               0x28

+/* ABS_MISC+x is used by HID to assign to unknown axes. Note that they used to
+ * flow over into the MT definitions. For backwards-compatibility, we must
+ * not reassign [0x29-0x2e] */
+
 #define ABS_MT_SLOT            0x2f    /* MT slot being modified */
 #define ABS_MT_TOUCH_MAJOR     0x30    /* Major axis of touching ellipse */
 #define ABS_MT_TOUCH_MINOR     0x31    /* Minor axis (omit if circular) */
--

1.8.5.1