Re: [PATCH 5/5] HID: sony: Handle multiple touch events input record

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

On Oct 05 2016 or thereabouts, Roderick Colenbrander wrote:
> On Wed, Oct 5, 2016 at 8:29 AM, Simon Wood <simon@mungewell.org> wrote:
> > On Wed, October 5, 2016 2:35 am, Benjamin Tissoires wrote:
> >> On Oct 04 2016 or thereabouts, Roderick Colenbrander wrote:
> >
> >>> +            /*
> >>> +             * The first 7 bits of the first byte is a counter and bit 8 is
> >>> +             * a touch indicator that is 0 when pressed and 1 when not
> >>> +             * pressed.
> >>> +             * The next 3 bytes are two 12 bit touch coordinates, X and Y.
> >>> +             * The data for the second touch is in the same format and
> >>> +             * immediately follows the data for the first.
> >>> +             */
> >>> +            for (n = 0; n < 2; n++) {
> >>> +                    u16 x, y;
> >>> +                    bool active;
> >>> +
> >>> +                    x = rd[offset+1] | ((rd[offset+2] & 0xF) << 8);
> >>> +                    y = ((rd[offset+2] & 0xF0) >> 4) | (rd[offset+3] << 4);
> >>> +
> >>> +                    active = !(rd[offset] >> 7);
> >>> +                    input_mt_slot(input_dev, n);
> >>>
> >>
> >> Just to be sure, the device reports 2 touches only, and the
> >> "num_touch_data" chunks are just the history of these 2 touches, the
> >> last chunk being the last known touches?
> >
> > FYI - Community knowledge/understanding...
> > http://www.psdevwiki.com/ps4/DS4-BT#HID_INPUT_reports
> >
> > Simon
> >
> 
> Hi Ben and Simon,
> 
> Correct, the DS4 sends a touch history. The last element is the
> latest. An input report can contain multiple touch samples, because
> the device internally samples at a rate which is higher than at which
> it generates HID reports. On USB you can easily see multiple touch
> events and it is even easier on Bluetooth (especially if it is set to
> a low frequency). The extra history is important for gestures.

OK, so if it's important, you need to actually send it by adding
input_mt_sync_frame() and input_sync() calls. Otherwise, the values will
just get mangled by the kernel in evdev and everything happens as if you
just sent the last pair in the history.

The first 4 patches are IMO mergeable, but this one will need a little
bit more polish to actually forward the events.

Cheers,
Benjamin

> 
> Thanks,
> Roderick