Re: [PATCH 1/5] m68k: Fix atari mouse movement

Hi Michael,

CC linux-input

On Fri, 14 Aug 2026 at 05:17, Michael Schmitz <[email protected]> wrote:
> From: Miro Kropacek <[email protected]>
>
> Kernels are built with -funsigned-char since version 6.2, resulting
> in signed mouse position deltas getting misinterpreted as unsigned.
>
> Cast deltas passed in (unsigned) scancode buffer to correctly
> interpret sign.
>
> Fixes: 3bc753c06dd02a35 ("kbuild: treat char as always unsigned")
> Link: https://lists.debian.org/debian-68k/2026/08/msg00000.html
> Signed-off-by: Miro Kropacek <[email protected]>
> Reviewed-by: Michael Schmitz <[email protected]>

Since you're now in the path to upstream, you should add your SoB here
(applies to all patches).

> --- a/drivers/input/mouse/atarimouse.c
> +++ b/drivers/input/mouse/atarimouse.c
> @@ -70,9 +70,12 @@ static void atamouse_interrupt(char *buf)

Alternative, you could change/restore the function's signature to take a
"signed char *".

>         atari_mouse_buttons = buttons;
>  #endif
>
> -       /* only relative events get here */
> -       dx = buf[1];
> -       dy = buf[2];
> +       /* only relative events get here; the IKBD sends signed 8-bit
> +        * deltas, and the kernel builds with -funsigned-char since 6.2,
> +        * so an explicit signed cast is required
> +        */
> +       dx = (s8)buf[1];
> +       dy = (s8)buf[2];
>
>         input_report_rel(atamouse_dev, REL_X, dx);
>         input_report_rel(atamouse_dev, REL_Y, dy);

Regardless:
Reviewed-by: Geert Uytterhoeven <[email protected]>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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