Re: [PATCH] Input: xpad - Change buttons the D-Pad gets mapped as to BTN_DPAD_*

[Cameron Gutman <aicommander@gmail.com>]

On Sat, Nov 1, 2025 at 12:52 AM Vicki Pfau <vi@endrift.com> wrote:
>
>
>
> On 10/31/25 8:18 PM, Cameron Gutman wrote:
> > On Sun, Jul 27, 2025 at 3:23 AM Dmitry Torokhov
> > <dmitry.torokhov@gmail.com> wrote:
> >>
> >> On Tue, Jul 01, 2025 at 08:47:40PM -0700, Vicki Pfau wrote:
> >>> Since dance pads can have both up/down or left/right pressed at the same time,
> >>> by design, they are not suitable for mapping the buttons to axes. Historically,
> >>> this driver mapped the D-pad to BTN_TRIGGER_HAPPY1-4 in these cases, and before
> >>> that as mouse buttons. However, BTN_DPAD_* exists for this and makes far more
> >>> sense than the arbitrary mapping it was before.
> >>>
> >>> Signed-off-by: Vicki Pfau <vi@endrift.com>
> >>
> >> This unfortunately changes existing mappings, but I guess new events are
> >> better than old ones...
> >>
> >> Applied, thank you.
> >
> > Unfortunately this mapping change caused major userspace breakages.
>
> This is unfortunate, however,>
> > I think it needs to be reverted.
> >
> > [0]: https://blog.dwickham.me.uk/why-your-xbox-360-wireless-controllers-d-pad-is-now-wrong-and-how-to-fix-it
> > [1]: https://github.com/libsdl-org/SDL/issues/14324
> > [2]: https://github.com/libsdl-org/SDL/pull/14339
>
> None of these pages suggest reverting the changes. The blog post suggests that these mappings are correct, and that the libraries need to be fixed. Reverting it is mentioned as an absolute last case scenario. The SDL issues say they need more testing, not an outright reversion.

Breaking userspace is the #1 thing we cannot do as Linux kernel developers.

The fact that it broke enough people to get a blog post is reason
enough to revert.

>
> Reverting this is solely reverting to an old, uncomfortable status quo instead of actually fixing the things that broke. If this gets reverted, presumably more stuff will ship this broken code that will break if we ever fix this issue again, instead of things getting progressively fixed.
>

The "broken" 360 wireless mapping has been used since wireless adapter
support was first implemented in 2008 [0].

There's decades of software out there that already has workarounds for
these devices that we must not break.

We can send the proper button codes for new controllers, but I think
we have to leave existing devices alone.

[0]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=99de0912be6f384fc31c8e8e7ba0850d0d670385

> The abandonware being broken is unfortunate, but things like Steam Input exist specifically to work around issues like that.
>

This isn't just breaking abandonware. It's breaking the *latest*
releases of SDL2 and SDL3.

We cannot depend on third-party software like Steam Input to avoid
breaking userspace,
nor can we depend on distros to update their SDL versions in lockstep
with the kernel.

> >
> >>
> >> --
> >> Dmitry
> >>
>
> Vicki
>