The joystick max buttons 80 limitation comes from
#define BTN_JOYSTICK 0x120
#define BTN_DEAD 0x12f
#define BTN_TRIGGER_HAPPY 0x2c0
#define KEY_MAX 0x2ff
include/uapi/linux/input-event-codes.h
according to function hidinput_configure_usage() in file drivers/hid/hid-input.c
the joystick button mapping is not a continues space
generally speaking, the mapping space is from
1. BTN_JOYSTICK~BTN_DEAD
2. BTN_TRIGGER_HAPPY~KEY_MAX
Finally, I got the max limitation is 80.
The patch is expanding KEY_MAX from 0x2ff to 4ff
and the change has been verified on 104 button USB HID device on Ubuntu
Signed-off-by: Wei Shuai <cpuwolf@xxxxxxxxx>
---
include/linux/mod_devicetable.h | 2 +-
include/uapi/linux/input-event-codes.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 8d764aab29de..35eb59ae1f19 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -311,7 +311,7 @@ struct pcmcia_device_id {
/* Input */
#define INPUT_DEVICE_ID_EV_MAX 0x1f
#define INPUT_DEVICE_ID_KEY_MIN_INTERESTING 0x71
-#define INPUT_DEVICE_ID_KEY_MAX 0x2ff
+#define INPUT_DEVICE_ID_KEY_MAX 0x4ff
#define INPUT_DEVICE_ID_REL_MAX 0x0f
#define INPUT_DEVICE_ID_ABS_MAX 0x3f
#define INPUT_DEVICE_ID_MSC_MAX 0x07
diff --git a/include/uapi/linux/input-event-codes.h
b/include/uapi/linux/input-event-codes.h
index b6a835d37826..ad1b9bed3828 100644
--- a/include/uapi/linux/input-event-codes.h
+++ b/include/uapi/linux/input-event-codes.h
@@ -774,7 +774,7 @@
/* We avoid low common keys in module aliases so they don't get huge. */
#define KEY_MIN_INTERESTING KEY_MUTE
-#define KEY_MAX 0x2ff
+#define KEY_MAX 0x4ff
#define KEY_CNT (KEY_MAX+1)
/*
--
2.17.1
