linux-kernel - Re: [PATCH] Input: Change BTN_TOOL_FINGER falg when HOVER event trigger

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Date:	Thu, 31 Mar 2016 11:17:30 -0700
From:	'Dmitry Torokhov' <dmitry.torokhov@...il.com>
To:	DusonLin <dusonlin@....com.tw>
Cc:	Linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
	'Charles Mooney' <charliemooney@...gle.com>,
	'jeff' <jeff.chuang@....com.tw>, 'Phoenix' <phoenix@....com.tw>
Subject: Re: [PATCH] Input: Change BTN_TOOL_FINGER falg when HOVER event
 trigger

On Wed, Mar 30, 2016 at 05:49:12PM +0800, DusonLin wrote:
> Hello Dmitry,
> 
> Please check my response below, thanks.
> 
> 
> -----Original Message-----
> From: 'Dmitry Torokhov' [mailto:dmitry.torokhov@...il.com] 
> Sent: Wednesday, March 30, 2016 10:31 AM
> To: DusonLin
> Cc: Linux-kernel@...r.kernel.org; linux-input@...r.kernel.org; 'Charles Mooney'; 'jeff'; 'Phoenix'
> Subject: Re: [PATCH] Input: Change BTN_TOOL_FINGER falg when HOVER event trigger
> 
> Hi Duson,
> 
> On Wed, Mar 30, 2016 at 10:02:02AM +0800, DusonLin wrote:
> > Only ABS_DISTANCE is not enough for upper OS  to distiguish hover 
> > event be triggered from object form faraway to and close touchpad 
> > surface or from object prepare to leave the touchpad surface. We add 
> > BNT_TOOL_FINGER to help it.
> > 
> >                  Object_at_faraway   object_at_hover_area  object_touch_touchpad
> >       BTN_TOUCH         0                      0                    1
> > BTN_TOOL_FINGER         0                      1                    1
> >    ABS_DISTANCE         0                      1                    0
> > 
> > Signed-off by: Duson Lin <dusonlin@....com.tw>
> > ---
> > drivers/input/mouse/elan_i2c_core.c |   14 +++++++++-----
> > 1 file changed, 9 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/input/mouse/elan_i2c_core.c 
> > b/drivers/input/mouse/elan_i2c_core.c
> > index 2f58985..9392a8c 100644
> > --- a/drivers/input/mouse/elan_i2c_core.c
> > +++ b/drivers/input/mouse/elan_i2c_core.c
> > @@ -4,7 +4,7 @@
> >   * Copyright (c) 2013 ELAN Microelectronics Corp.
> >   *
> >   * Author: 林政維 (Duson Lin) <dusonlin@....com.tw>
> > - * Version: 1.6.0
> > + * Version: 1.6.1
> >   *
> >   * Based on cyapa driver:
> >   * copyright (c) 2011-2012 Cypress Semiconductor, Inc.
> > @@ -845,23 +845,27 @@ static void elan_report_absolute(struct 
> > elan_tp_data *data, u8 *packet) {
> >       struct input_dev *input = data->input;
> >       u8 *finger_data = &packet[ETP_FINGER_DATA_OFFSET];
> > -       int i;
> > +      int i, valid_count = 0;
> 
> This appears all whitespace-damaged.
> [duson] will do.
> 
> >       u8 tp_info = packet[ETP_TOUCH_INFO_OFFSET];
> >       u8 hover_info = packet[ETP_HOVER_INFO_OFFSET];
> >       bool contact_valid, hover_event;
> > 
> > -       hover_event = hover_info & 0x40;
> > +      hover_event = (hover_info & 0x40);
> 
> We do not need parentheses here.
> [duson] will do.
> 
> >       for (i = 0; i < ETP_MAX_FINGERS; i++) {
> >               contact_valid = tp_info & (1U << (3 + i));
> >               elan_report_contact(data, i, contact_valid, 
> > finger_data);
> > 
> > -               if (contact_valid)
> > +              if (contact_valid) {
> >                       finger_data += ETP_FINGER_DATA_LEN;
> > +                      valid_count++;
> > +              }
> >       }
> > 
> >        input_report_key(input, BTN_LEFT, tp_info & 0x01);
> > +      input_report_key(input, BTN_TOOL_FINGER,
> > +                      ((hover_event != 0) | (valid_count > 0)));
> 
> You do not want to use "bitwise or" here.
> 
> >       input_report_abs(input, ABS_DISTANCE, hover_event != 0);
> > -       input_mt_report_pointer_emulation(input, true);
> > +      input_mt_report_pointer_emulation(input, false);
> 
> I wonder if we should teach input_mt_report_pointer_emulation() to handle hover properly.
> [duson] But, it looks like the hover is not standard function and not all of touchpad support this function, 
>        Even though, we still teach inpu_mt_report_pointer_emulation() to handle this function?

Yes, something like this:

If device supports ABS_DISTANCE and does not support ABS_MT_DISTANCE and
ABS_DISTANCE != 0 is reported in current frame and there are no other
contacts then report BTN_TOOL_FINGER.

Thanks.

-- 
Dmitry