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

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Sat, Jul 16, 2016 at 03:33:12PM -0700, Ping Cheng wrote:
> On Sat, Jul 16, 2016 at 2:58 PM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
> > On July 16, 2016 2:32:27 PM PDT, Ping Cheng <pinglinux@gmail.com> wrote:
> >>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.
> >
> > But unless I missed some other patch from you this driver passes 0 as flags to input_mt_init_slots() and by removing the double-tap bit we are breaking the driver.
> 
> Oh, I see where you are ;). I assumed INPUT_MT_DIRECT was there. My
> bad eyes ;-)!  We'd be better to change
> 
> input_mt_init_slots(dev, 2, 0);
> 
> to
> 
> input_mt_init_slots(dev, 2, INPUT_MT_DIRECT);
> 
> Do you want me to submit a new version or can you update it locally?

Ping,

If you look at input_mt_init_slots() we only set the doubletap bit
if we are using INPUT_MT_POINTER, but you are asking me to set
INPUT_MT_DIRECT (which is correct property given that we are dealing
with the touchscreen). Also, input_mt_sync_frame() passes use_count ==
true to input_mt_report_pointer_emulation() (which would enable
reporting of <n>-tap events) only if device has INPUT_MT_POINTER
property.

The while premise of this patch seems wrong. wacom.ko deals with
tablets, wacom_w8001 is for a touchscreen. They behave differently.

-- 
Dmitry