HID: input: Increase maximum number of joystick buttons

[PATCH] HID: input: Increase maximum number of joystick buttons

Posted by Ivan Gorinov 1 month, 2 weeks ago

This patch increases the limit from 80 to 112 key codes.

If a joystick has 80 or fewer buttons, mapping stays the same.

If a joystick has more than 80 buttons:

  Map buttons [  0 ..  15 ] to key codes starting with BTN_JOYSTICK;
  Map buttons [ 16 ..  47 ] to key codes starting with KEY_MACRO1;
  Map buttons [ 48 .. 111 ] to key codes starting with BTN_TRIGGER_HAPPY.

Signed-off-by: Ivan Gorinov <linux-kernel@altimeter.info>
---
 drivers/hid/hid-input.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 2633fcd8f910..c6159f96de04 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -763,7 +763,13 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
 				if (code <= 0xf)
 					code += BTN_JOYSTICK;
 				else
-					code += BTN_TRIGGER_HAPPY - 0x10;
+					if (field->maxusage <= 80)
+						code += BTN_TRIGGER_HAPPY - 0x10;
+					else
+						if (code <= 0x2f)
+							code += KEY_MACRO1 - 0x10;
+						else
+							code += BTN_TRIGGER_HAPPY - 0x30;
 				break;
 		case HID_GD_GAMEPAD:
 				if (code <= 0xf)
-- 
2.43.0

Re: [PATCH] HID: input: Increase maximum number of joystick buttons

Posted by tomasz.pakula.oficjalny@gmail.com 1 month ago

On Sat, 2025-12-20 at 19:41 +0000, Ivan Gorinov wrote:
> This patch increases the limit from 80 to 112 key codes.
> 
> If a joystick has 80 or fewer buttons, mapping stays the same.
> 
> If a joystick has more than 80 buttons:
> 
>   Map buttons [  0 ..  15 ] to key codes starting with BTN_JOYSTICK;
>   Map buttons [ 16 ..  47 ] to key codes starting with KEY_MACRO1;
>   Map buttons [ 48 .. 111 ] to key codes starting with BTN_TRIGGER_HAPPY.
> 
> Signed-off-by: Ivan Gorinov <linux-kernel@altimeter.info>
> ---
>  drivers/hid/hid-input.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index 2633fcd8f910..c6159f96de04 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -763,7 +763,13 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
>  				if (code <= 0xf)
>  					code += BTN_JOYSTICK;
>  				else
> -					code += BTN_TRIGGER_HAPPY - 0x10;
> +					if (field->maxusage <= 80)
> +						code += BTN_TRIGGER_HAPPY - 0x10;
> +					else
> +						if (code <= 0x2f)
> +							code += KEY_MACRO1 - 0x10;
> +						else
> +							code += BTN_TRIGGER_HAPPY - 0x30;
>  				break;
>  		case HID_GD_GAMEPAD:
>  				if (code <= 0xf)

As stated previously by Dmitry when I tried to increase the KEY_MAX for
the same reason, the defined usages have their place and shouldn't be
misused. I finally understood that and I have to say that this is just
more confusing and a dirty hack, certainly used by some drivers because
it still works with SDL and Wine (they only care about the usage index).

I'm working on a proper solution with a new event type that will only
send button number (starting from 1 as does plain HID) and it's value.

This will support up to 65535 (u16) buttons and should be enough for
years to come :D I'll make sure to CC you when I'll send RFC.

Re: [PATCH] HID: input: Increase maximum number of joystick buttons

Posted by Ivan Gorinov 1 month ago

On Sat, Jan 03, 2026 at 08:26:55PM +0100, tomasz.pakula.oficjalny@gmail.com wrote:
> On Sat, 2025-12-20 at 19:41 +0000, Ivan Gorinov wrote:
> > This patch increases the limit from 80 to 112 key codes.
> > 
> > If a joystick has 80 or fewer buttons, mapping stays the same.
> > 
> > If a joystick has more than 80 buttons:
> > 
> >   Map buttons [  0 ..  15 ] to key codes starting with BTN_JOYSTICK;
> >   Map buttons [ 16 ..  47 ] to key codes starting with KEY_MACRO1;
> >   Map buttons [ 48 .. 111 ] to key codes starting with BTN_TRIGGER_HAPPY.
> > 
> 
> As stated previously by Dmitry when I tried to increase the KEY_MAX for
> the same reason, the defined usages have their place and shouldn't be
> misused. I finally understood that and I have to say that this is just
> more confusing and a dirty hack, certainly used by some drivers because
> it still works with SDL and Wine (they only care about the usage index).
> 
> I'm working on a proper solution with a new event type that will only
> send button number (starting from 1 as does plain HID) and it's value.
> 
> This will support up to 65535 (u16) buttons and should be enough for
> years to come :D I'll make sure to CC you when I'll send RFC.

Thank you! I learned how to map more than 80 buttons by overriding function
hid_driver.input_mapping from your contribution to JacKeTUs/universal-pdiff
and used the same idea in my recent changes in the hid-winwing module.

Good luck in your work on new event type!
I will test your changes with my Orion2/TGRIP-18 combo.

Meanwhile, this patch could allow existing software (for example, X-Plane 12)
to work with more input devices without any changes in userspace.