On Mon, Feb 02, 2015 at 02:15:58PM -0500, Benjamin Tissoires wrote:
> When tapping a clickpad with two fingers, there is a chance that the
> sensor sees first only one finger, and at the next scan only the
> second one.
> In this case, the sensors says that there has been only one finger
> on the clickpad, which moved really fast between two scans.
>
> We can try to counter this by adding a limit to what an actual finger
> can move between 2 scans.
> A distance of 1cm between two scans for one finger seems reasonable.
>
> However, this is not really accurate because the resolution in X and in Y
> differs. But heh, that's how the in-kernel tracking works right now, and
> its job is quite good, even with this approximation.
>
> This parameter solves most of the jumps observed, not all of them however.
> But this is a hardware defect, and we might not be able to get something
> better without much heavier computations.
>
> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=76722
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com>
Applied, thank you.
> ---
> drivers/input/mouse/synaptics.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> index a3692e3..bee0387 100644
> --- a/drivers/input/mouse/synaptics.c
> +++ b/drivers/input/mouse/synaptics.c
> @@ -67,6 +67,9 @@
> #define X_MAX_POSITIVE 8176
> #define Y_MAX_POSITIVE 8176
>
> +/* maximum ABS_MT_POSITION displacement (in mm) */
> +#define DMAX 10
> +
>
> /*****************************************************************************
> * Stuff we need even when we do not want native Synaptics support
>
> ****************************************************************************/
> @@ -809,7 +812,7 @@ static void synaptics_report_mt_data(struct psmouse
> *psmouse,
> pos[i].y = synaptics_invert_y(hw[i]->y);
> }
>
> - input_mt_assign_slots(dev, slot, pos, nsemi, 0);
> + input_mt_assign_slots(dev, slot, pos, nsemi, DMAX * priv->x_res);
>
> for (i = 0; i < nsemi; i++) {
> input_mt_slot(dev, slot[i]);
> --
> 2.1.0
>
--
Dmitry
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
