[systemd-devel] [PATCH] input_id: Identify scroll-wheel device on Trust TB7300 tablet as keyboard

[Peter Hutterer]

On Sat, Apr 11, 2015 at 03:27:46PM +0200, Hans de Goede wrote:
> The Trust TB7300 (relabelled Waltop?) tablet has a scrollwheel which shows
> up as a /dev/input/event# node all by itself. Currently input_id does not
> set any ID_INPUT_FOO attr on this causing it it to not be recognized by
> Xorg / libinput.
> 
> This commit fixes this by marking it with ID_INPUT_KEY.
> 
> Cc: Sjoerd Timmer <themba at randomdata.nl>
> Reported-by: Sjoerd Timmer <themba at randomdata.nl>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
>  src/udev/udev-builtin-input_id.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/src/udev/udev-builtin-input_id.c b/src/udev/udev-builtin-input_id.c
> index ecfc447..f07f86e 100644
> --- a/src/udev/udev-builtin-input_id.c
> +++ b/src/udev/udev-builtin-input_id.c
> @@ -262,6 +262,13 @@ static int builtin_input_id(struct udev_device *dev, int argc, char *argv[], boo
>                  test_pointers(dev, bitmask_ev, bitmask_abs, bitmask_key,
>                                bitmask_rel, bitmask_props, test);
>                  test_key(dev, bitmask_ev, bitmask_key, test);
> +                /*
> +                 * The scrollwheel on some devices is a device all by itself,
> +                 * treat this as a keyboard with just a scrollwheel.
> +                 */
> +                if (bitmask_ev[0] == (BIT(EV_REL) | BIT(EV_SYN)) &&
> +                    bitmask_rel[0] == (bitmask_rel[0] & (BIT(REL_WHEEL) | BIT(REL_HWHEEL))))
> +                        udev_builtin_add_property(dev, test, "ID_INPUT_KEY", "1");

A simpler approach would be to return a value from test_pointers() if we set
anything there and then use that:

    is_pointer = test_pointers(.....);
    is_keyboard = test_key();

    if (!is_pointer && !is_keyboard &&
        test_bit(EV_REL) && (test_bit(REL_WHEEL) ||  test_bit(REL_HWHEEL)))
        udev_builtin_add_property();

I also wonder what the side effect is of setting ID_INPUT_KEY
on a device without EV_KEY but I can't really come up with a better tag
(short of introducing a completely new one).

Cheers,
  Peter



>          }
>  
>          devnode = udev_device_get_devnode(dev);
> -- 
> 2.3.4
>