On Tue, Oct 28, 2014 at 04:47:56PM -0400, Benjamin Tissoires wrote:
> Hi Chung-yih,
>
> On Mon, Oct 27, 2014 at 6:08 AM, Chung-yih Wang <cywang@xxxxxxxxxxxx> wrote:
> > From the definition of BTN_TOUCH, BTN_TOOL_<name> and BTN_TOUCH codes
> > are orthogonal. BTN_TOUCH should be zero if there is no physical contact
> > happened on device. With ABS_MT_DISTANCE information, the patch uses
> > touch_count and finger_count to get the final reporting code for
> > BTN_TOUCH and BTN_TOOL_<name>, respectively.
> >
> > Signed-off-by: Chung-yih Wang <cywang@xxxxxxxxxxxx>
> > ---
> > drivers/input/input-mt.c | 15 ++++++++++-----
> > 1 file changed, 10 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
> > index fbe29fc..a2ab8e3 100644
> > --- a/drivers/input/input-mt.c
> > +++ b/drivers/input/input-mt.c
> > @@ -192,18 +192,21 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
> > {
> > struct input_mt *mt = dev->mt;
> > struct input_mt_slot *oldest;
> > - int oldid, count, i;
> > + int oldid, i;
> > + int touch_count, finger_count;
> >
> > if (!mt)
> > return;
> >
> > oldest = NULL;
> > oldid = mt->trkid;
> > - count = 0;
> > + touch_count = 0;
> > + finger_count = 0;
> >
> > for (i = 0; i < mt->num_slots; ++i) {
> > struct input_mt_slot *ps = &mt->slots[i];
> > int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
> > + int distance = input_mt_get_value(ps, ABS_MT_DISTANCE);
>
> I don't really like this statement, even if it works. Some devices do
> not report ABS_MT_DISTANCE, and the value for them should not be
> considered as '0' but 'undefined'.
I think it incidentally still 0 as we zero out memory we allocate.
>
> >
> > if (id < 0)
> > continue;
> > @@ -211,12 +214,14 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
> > oldest = ps;
> > oldid = id;
> > }
> > - count++;
> > + finger_count++;
> > + if (distance == 0)
>
> I'd rather test here if ABS_MT_DISTANCE is used, and then if the value is 0.
>
> > + touch_count++;
I do not think we should include hovering contacts into finger_count
either. I.e if I have one finger touching and one finger hovering we
should be emitting BTN_TOOL_FINGER and not BTN_TOOL_DOUBLETAP.
> > }
> >
> > - input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
> > + input_event(dev, EV_KEY, BTN_TOUCH, touch_count > 0);
>
> For the record, I *think* this will not break user space. This is used
> in the touchpad part of libinput, and does not seemed to be impacted
> by the change.
> Adding Peter and Hans in CC who can tell us if I am assuming right.
>
> Cheers,
> Benjamin
>
> > if (use_count)
> > - input_mt_report_finger_count(dev, count);
> > + input_mt_report_finger_count(dev, finger_count);
> >
> > if (oldest) {
> > int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
> > --
> > 2.1.2
> >
Thanks.
--
Dmitry
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