Documentation/input/devices/xpad.rst

Source file repositories/reference/linux-study-clean/Documentation/input/devices/xpad.rst

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Documentation/input/devices/xpad.rst
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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=======================================================
xpad - Linux USB driver for Xbox compatible controllers
=======================================================

This driver exposes all first-party and third-party Xbox compatible
controllers. It has a long history and has enjoyed considerable usage
as Windows' xinput library caused most PC games to focus on Xbox
controller compatibility.

Due to backwards compatibility all buttons are reported as digital.
This only affects Original Xbox controllers. All later controller models
have only digital face buttons.

Rumble is supported on some models of Xbox 360 controllers but not of
Original Xbox controllers nor on Xbox One controllers. As of writing
the Xbox One's rumble protocol has not been reverse-engineered but in
the future could be supported.


Notes
=====

The number of buttons/axes reported varies based on 3 things:

- if you are using a known controller
- if you are using a known dance pad
- if using an unknown device (one not listed below), what you set in the
  module configuration for "Map D-PAD to buttons rather than axes for unknown
  pads" (module option dpad_to_buttons)

If you set dpad_to_buttons to N and you are using an unknown device
the driver will map the directional pad to axes (X/Y).
If you said Y it will map the d-pad to buttons, which is needed for dance
style games to function correctly. The default is Y.

dpad_to_buttons has no effect for known pads. A erroneous commit message
claimed dpad_to_buttons could be used to force behavior on known devices.
This is not true. Both dpad_to_buttons and triggers_to_buttons only affect
unknown controllers.


Normal Controllers
------------------

With a normal controller, the directional pad is mapped to its own X/Y axes.
The jstest-program from joystick-1.2.15 (jstest-version 2.1.0) will report 8
axes and 10 buttons.

All 8 axes work, though they all have the same range (-32768..32767)
and the zero-setting is not correct for the triggers (I don't know if that
is some limitation of jstest, since the input device setup should be fine. I
didn't have a look at jstest itself yet).

All of the 10 buttons work (in digital mode). The six buttons on the
right side (A, B, X, Y, black, white) are said to be "analog" and
report their values as 8 bit unsigned, not sure what this is good for.

I tested the controller with quake3, and configuration and
in game functionality were OK. However, I find it rather difficult to
play first person shooters with a pad. Your mileage may vary.


Xbox Dance Pads
---------------

When using a known dance pad, jstest will report 6 axes and 14 buttons.

For dance style pads (like the redoctane pad) several changes
have been made.  The old driver would map the d-pad to axes, resulting
in the driver being unable to report when the user was pressing both

Annotation

Implementation Notes