* Fwd: Linux General Joystick Max buttons limitation 80
[not found] <CACa7zynY07xp3hhe5SA4wcGxJB6shc9qoos-BOL2CeXPEobzuA@mail.gmail.com>
@ 2020-07-09 23:10 ` Wei Shuai
2020-07-10 13:15 ` Wei Shuai
0 siblings, 1 reply; 2+ messages in thread
From: Wei Shuai @ 2020-07-09 23:10 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: linux-input
Dear Joystick Maintainer,
we found Linux kernel has max joystick buttons up to 80, no more
We are selling a USB joystick device QMCP737C for flight simulator,
which is nothing but a common USB joystick. it has 104 buttons
Product link
https://x-plane.vip/quickmade/qmcp737c/
it works good on Windows, Mac, but not on Linux.
Linux kernel exposes /dev/input/js0 max to 80 buttons, but we have 104 buttons.
I did a lot of google search, but nothing I got. then I have to look
at Kernel source, to find out where this number max 80 comes from
Eventually I found the final limitation
#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 continuous space, general speak
the mapping space is from
BTN_JOYSTICK~BTN_DEAD
BTN_TRIGGER_HAPPY~KEY_MAX
and finally I got the max limitation is 80.
My question is why KEY_MAX is 0x2ff? this number 0x2ff looks like it
does not align with char?integer? the answer is no
so may I ask to expand KEY_MAX to such as 0x4ff? or you need me to
submit patch for it, I am OK
Thank you
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Linux General Joystick Max buttons limitation 80
2020-07-09 23:10 ` Fwd: Linux General Joystick Max buttons limitation 80 Wei Shuai
@ 2020-07-10 13:15 ` Wei Shuai
0 siblings, 0 replies; 2+ messages in thread
From: Wei Shuai @ 2020-07-10 13:15 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)...
Dear Dmitry Torokhov,
I have tried this change on Ubuntu, it really works. The small fix
will break the limitation of the max button number of Joystick.
Please help to review the patch, I have sent the patch in a different
email thread.
Wei Shuai <cpuwolf@gmail.com> 于2020年7月10日周五 上午7:10写道:
>
> Dear Joystick Maintainer,
>
> we found Linux kernel has max joystick buttons up to 80, no more
>
> We are selling a USB joystick device QMCP737C for flight simulator,
> which is nothing but a common USB joystick. it has 104 buttons
>
> Product link
> https://x-plane.vip/quickmade/qmcp737c/
>
> it works good on Windows, Mac, but not on Linux.
> Linux kernel exposes /dev/input/js0 max to 80 buttons, but we have 104 buttons.
>
> I did a lot of google search, but nothing I got. then I have to look
> at Kernel source, to find out where this number max 80 comes from
>
> Eventually I found the final limitation
>
> #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 continuous space, general speak
> the mapping space is from
>
> BTN_JOYSTICK~BTN_DEAD
> BTN_TRIGGER_HAPPY~KEY_MAX
>
> and finally I got the max limitation is 80.
>
> My question is why KEY_MAX is 0x2ff? this number 0x2ff looks like it
> does not align with char?integer? the answer is no
>
> so may I ask to expand KEY_MAX to such as 0x4ff? or you need me to
> submit patch for it, I am OK
>
> Thank you
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2020-07-10 13:15 UTC | newest]
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2020-07-09 23:10 ` Fwd: Linux General Joystick Max buttons limitation 80 Wei Shuai
2020-07-10 13:15 ` Wei Shuai
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