Re: [PATCH 2/2 v2] input: wacom_w8001 - cleanup 2FG touch code

[Ping Cheng <pinglinux@gmail.com>]

On Fri, Jul 15, 2016 at 10:33 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> On Fri, Jul 15, 2016 at 06:19:41PM -0700, Ping Cheng wrote:
>> On Friday, July 15, 2016, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
>>
>> > On Fri, Jul 15, 2016 at 04:26:25PM -0700, Ping Cheng wrote:
>> > > input_mt_sync_frame is used by other wacom devices in wacom_wac.c
>> > > to close the frame and emulate pointer events. Let's follow them.
>> > >
>> > > Touch events aren't multiplexed over the same device anymore, the
>> > > use of ABS_MT_TOOL_TYPE is superfluous.
>> >
>> > All of our touchscreen report the finger tool events, even if it is the
>> > only "tool" that is being used. Does it cause problems?
>> >
>>
>> No, it does not cause problem, with/without ABS_MT_TOOL_TYPE being set.
>> Testing result shows all touch data are reported whether we explicitly set
>> ABS_MT_TOOL_TYPE upfront or not. Plus, ABS_MT_TOOL_TYPE is not set in
>> wacom.ko. We'd like to be in sync with wacom.ko.
>>
>> The following comments for input_mt_report_slot_state in input-mt.c
>> explains the reason:
>>
>> "* Reports a contact via ABS_MT_TRACKING_ID, and optionally
>>  * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
>>  * inactive, or if the tool type is changed, a new tracking id is
>>  * assigned to the slot. The tool type is only reported if the
>>  * corresponding absbit field is set."
>>
>> MT_TOOL_TYPE is necessary if we report both pen and touch on the same
>> interface. That is not true for this series of devices any more..
>>
>>
>> > >
>> > > Signed-off-by: Ping Cheng <pingc@wacom.com>
>> > > Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
>> > > ---
>> > > v2: moved input_abs_set_res into a separate patch, as suggested by
>> > > Dmitry.
>> > > ---
>> > >  drivers/input/touchscreen/wacom_w8001.c | 15 ++-------------
>> > >  1 file changed, 2 insertions(+), 13 deletions(-)
>> > >
>> > > diff --git a/drivers/input/touchscreen/wacom_w8001.c
>> > b/drivers/input/touchscreen/wacom_w8001.c
>> > > index 7e807af..541a8df 100644
>> > > --- a/drivers/input/touchscreen/wacom_w8001.c
>> > > +++ b/drivers/input/touchscreen/wacom_w8001.c
>> > > @@ -170,16 +170,8 @@ static void parse_multi_touch(struct w8001 *w8001)
>> > >               }
>> > >       }
>> > >
>> > > -     /* emulate single touch events when stylus is out of proximity.
>> > > -      * This is to make single touch backward support consistent
>> > > -      * across all Wacom single touch devices.
>> > > -      */
>> > > -     if (w8001->type != BTN_TOOL_PEN &&
>> > > -                         w8001->type != BTN_TOOL_RUBBER) {
>> > > -             w8001->type = count == 1 ? BTN_TOOL_FINGER : KEY_RESERVED;
>> > > -             input_mt_report_pointer_emulation(dev, true);
>> > > -     }
>> > > -
>> > > +     w8001->type = KEY_RESERVED;
>> > > +     input_mt_sync_frame(dev);
>> > >       input_sync(dev);
>> > >  }
>> > >
>> > > @@ -508,7 +500,6 @@ static int w8001_setup_touch(struct w8001 *w8001,
>> > char *basename,
>> > >       case 5:
>> > >               w8001->pktlen = W8001_PKTLEN_TOUCH2FG;
>> > >
>> > > -             __set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
>> >
>> > Who is setting this bit then?
>> >
>>
>> All MT related bits are set by input_mt_init_slots in input-mt.c, including
>> BTN_TOOL_DOUBLETAP, if necessary.
>
> Doesn't this only happen if you call input_mt_init_slots with
> INPUT_MT_POINTER flag?

You are right. And that is what we want this driver to do - to be in
sync with wacom.ko and rely on input-mt for common actions.

Cheers,

Ping