[PATCH libevdev] Don't treat devices with (ABS_MT_SLOT - 1) as multitouch devices

[David Herrmann]

Hi

On Tue, Dec 10, 2013 at 2:02 AM, Peter Hutterer
<peter.hutterer at who-t.net> wrote:
> Some devices (PS3 sixaxis controller) merely have a bunch of axes, without the
> semantic information that linux/input.h requires. For those, the ABS_MT range
> may be merely another axis, not the special range that we need to treat it
> with.
>
> Use a simple heuristic: if ABS_MT_SLOT - 1 is enabled, don't treat ABS_MT as
> multitouch axes. The ABS_MT_SLOT - 1 axis is not used for a real axis.
>
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  libevdev/libevdev.c            |  5 +++--
>  libevdev/libevdev.h            |  9 +++++++++
>  test/test-libevdev-has-event.c | 33 +++++++++++++++++++++++++++++++++
>  3 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
> index 60bbbfc..6967e4b 100644
> --- a/libevdev/libevdev.c
> +++ b/libevdev/libevdev.c
> @@ -333,7 +333,8 @@ libevdev_set_fd(struct libevdev* dev, int fd)
>                                 goto out;
>
>                         dev->abs_info[i] = abs_info;
> -                       if (i == ABS_MT_SLOT) {
> +                       if (i == ABS_MT_SLOT &&
> +                           !libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT - 1)) {

Short comment here maybe? Not obvious at all and not everyone looks up
the comments in the header when reading code.

>                                 dev->num_slots = abs_info.maximum + 1;
>                                 dev->current_slot = abs_info.value;
>                         }
> @@ -627,7 +628,7 @@ update_key_state(struct libevdev *dev, const struct input_event *e)
>  static int
>  update_mt_state(struct libevdev *dev, const struct input_event *e)
>  {
> -       if (e->code == ABS_MT_SLOT) {
> +       if (e->code == ABS_MT_SLOT && dev->num_slots > -1) {
>                 int i;
>                 dev->current_slot = e->value;
>                 /* sync abs_info with the current slot values */
> diff --git a/libevdev/libevdev.h b/libevdev/libevdev.h
> index 2b6f48a..44aa3a6 100644
> --- a/libevdev/libevdev.h
> +++ b/libevdev/libevdev.h
> @@ -361,6 +361,15 @@ extern "C" {
>   *
>   * As with @ref bits, the logical state of the device as seen by the library
>   * depends on the caller using libevdev_next_event().
> + *
> + * The Linux kernel requires all axes on a device to have a semantic
> + * meaning, matching the axis names in linux/input.h. Some devices merely
> + * export a number of axes beyond the available axis list. For those
> + * devices, the multitouch information is invalid. Specfically, if a device
> + * provides the ABS_MT_SLOT axis AND also the (ABS_MT_SLOT - 1) axis, the
> + * device is not treated as multitouch device. No slot information is
> + * available and the ABS_MT axis range for these devices is treated as all
> + * other EV_ABS axes.

Stupid HID core uses ABS_MISC+x, yeah. But I remember Benjamin trying
to fix that recently. Anyhow, patch looks good. I think I will also
send a patch to linux-input at vger to add a comment to linux/input.h
about that.

Reviewed-by: David Herrmann <dh.herrmann at gmail.com>

Thanks
David

>   */
>
>  /**
> diff --git a/test/test-libevdev-has-event.c b/test/test-libevdev-has-event.c
> index 3aca23b..8beb8c4 100644
> --- a/test/test-libevdev-has-event.c
> +++ b/test/test-libevdev-has-event.c
> @@ -425,6 +425,38 @@ START_TEST(test_slot_number)
>  }
>  END_TEST
>
> +START_TEST(test_invalid_mt_device)
> +{
> +       struct uinput_device* uidev;
> +       struct libevdev *dev;
> +       int rc;
> +       const int nslots = 4;
> +       int value;
> +       struct input_absinfo abs[] = {  { ABS_X, 0, 2 },
> +               { ABS_Y, 0, 2 },
> +               { ABS_MT_POSITION_X, 0, 2 },
> +               { ABS_MT_POSITION_Y, 0, 2 },
> +               { ABS_MT_SLOT - 1, 0, 2 },
> +               { ABS_MT_SLOT, 0, nslots - 1 }};
> +
> +       rc = test_create_abs_device(&uidev, &dev, 6, abs,
> +                       -1);
> +       ck_assert_msg(rc == 0, "Failed to uinput device: %s", strerror(-rc));
> +
> +       ck_assert_int_eq(libevdev_get_num_slots(dev), -1);
> +       ck_assert_int_eq(libevdev_get_current_slot(dev), -1);
> +       ck_assert_int_eq(libevdev_set_slot_value(dev, 0, ABS_MT_POSITION_X, 0), -1);
> +       ck_assert_int_eq(libevdev_fetch_slot_value(dev, 0, ABS_MT_POSITION_X, &value), 0);
> +
> +       ck_assert(libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT - 1));
> +       ck_assert(libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT));
> +
> +       ck_assert_int_eq(libevdev_set_event_value(dev, EV_ABS, ABS_MT_SLOT, 1), 0);
> +       ck_assert(libevdev_get_event_value(dev, EV_ABS, ABS_MT_SLOT) == 1);
> +
> +       uinput_device_free(uidev);
> +} END_TEST
> +
>
>  START_TEST(test_device_name)
>  {
> @@ -1129,6 +1161,7 @@ libevdev_has_event_test(void)
>         tcase_add_test(tc, test_no_slots);
>         tcase_add_test(tc, test_slot_number);
>         tcase_add_test(tc, test_slot_init_value);
> +       tcase_add_test(tc, test_invalid_mt_device);
>         suite_add_tcase(s, tc);
>
>         tc = tcase_create("device info");
> --
> 1.8.3.1
>
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