Re: [PATCH v5] m68k: Fix atari mouse movement

[Geert Uytterhoeven]

On Wed, 21 Oct 2026 at 04:51, Michael Schmitz <schmitzmic@xxxxxxxxx> wrote:
> Am 21.10.2026 um 15:23 schrieb Miro Kropacek:
> > Kernels are built with -funsigned-char since version 6.2, resulting in
> > the signed 8-bit position deltas reported by the IKBD being
> > misinterpreted as unsigned.
> >
> > The hook is handed a raw IKBD packet, so take it as a byte stream and
> > apply the sign to the two displacement values alone.
> >
> > Fixes: 3bc753c06dd02a35 ("kbuild: treat char as always unsigned")
> > Link: https://lists.debian.org/debian-68k/2026/08/msg00000.html
> > Suggested-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> > Signed-off-by: Miro Kropacek <miro.kropacek@xxxxxxxxx>
> > Cc: linux-input <linux-input@xxxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v5:
> >
> > - take the packet as u8 * and cast only the two displacement values,
> >   as suggested; this drops the call-site cast v4 needed, and with it
> >   the -Wpointer-sign warning
> > - add the types include atarikb.h now relies on
> >
> > The same cast of the two displacement values was tested on an Atari
> > Falcon030 with CT60 in v1 of this patch; v5 differs from it only in the
> > type of the hook argument.
> >
> > Michael's Reviewed-by from v3 is dropped, as the approach has changed
> > twice since.
>
> Dmitry's reasoning makes sense to me, so we're back on v1 with no change
> in functionality.

If it's just a byte stream, one might not bother doing s/char/u8/, as both
are the same type anyway... and then we're really back at v1.

> Looks good to me, feel free to add my Reviewed-by if it helps get this
> merged.

Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
for the arch/m68k files:
Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds