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From:   "Johnny.Chuang" <johnny.chuang@emc.com.tw>
To:     "'Peter Hutterer'" <peter.hutterer@who-t.net>,
        "'Johnny Chuang'" <johnny.chuang.emc@gmail.com>
Cc:     "'Dmitry Torokhov'" <dmitry.torokhov@gmail.com>,
        "'Benjamin Tissoires'" <benjamin.tissoires@redhat.com>,
        <linux-kernel@vger.kernel.org>, <linux-input@vger.kernel.org>,
        "'Jennifer Tsai'" <jennifer.tsai@emc.com.tw>,
        "'James Chen'" <james.chen@emc.com.tw>,
        "'Paul Liang'" <paul.liang@emc.com.tw>,
        "'Jeff Chuang'" <jeff.chuang@emc.com.tw>
References: <1582766000-23023-1-git-send-email-johnny.chuang.emc@gmail.com> <20200227223608.GB1087116@jelly>
In-Reply-To: <20200227223608.GB1087116@jelly>
Subject: RE: [PATCH] Input: elants_i2c - Report resolution information for touch major
Date:   Mon, 2 Mar 2020 16:14:51 +0800
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> -----Original Message-----
> From: Peter Hutterer [mailto:peter.hutterer@who-t.net]
> Sent: Friday, February 28, 2020 6:36 AM
> To: Johnny Chuang
> Cc: Dmitry Torokhov; Benjamin Tissoires; linux-kernel@vger.kernel.org;
> linux-input@vger.kernel.org; Johnny Chuang; Jennifer Tsai; James Chen;
Paul
> Liang; Jeff Chuang
> Subject: Re: [PATCH] Input: elants_i2c - Report resolution information for
touch
> major
> 
> On Thu, Feb 27, 2020 at 09:13:20AM +0800, Johnny Chuang wrote:
> > From: Johnny Chuang <johnny.chuang@emc.com.tw>
> >
> > This patch supports reporting resolution for ABS_MT_TOUCH_MAJOR event.
> > This information is needed in showing pressure/width radius.
> >
> > Signed-off-by: Johnny Chuang <johnny.chuang@emc.com.tw>
> > ---
> >  drivers/input/touchscreen/elants_i2c.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/input/touchscreen/elants_i2c.c
> b/drivers/input/touchscreen/elants_i2c.c
> > index 4911799..14c577c 100644
> > --- a/drivers/input/touchscreen/elants_i2c.c
> > +++ b/drivers/input/touchscreen/elants_i2c.c
> > @@ -1309,6 +1309,7 @@ static int elants_i2c_probe(struct i2c_client
> *client,
> >  	input_set_abs_params(ts->input, ABS_MT_PRESSURE, 0, 255, 0, 0);
> >  	input_abs_set_res(ts->input, ABS_MT_POSITION_X, ts->x_res);
> >  	input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
> > +	input_abs_set_res(ts->input, ABS_MT_TOUCH_MAJOR, 1);
> 
> official resolution for absinfo is "units per mm", so a value of 3 would
> mean 3mm, is that correct?

Correct.
This resolution (1 unit/mm) is for all elan I2C touchscreen devices, 
including the touchscreen devices in the future.
This information is from our firmware members.

> 
> Not that it matters too much, since touch major is already all over the
> place and needs userspace overrides for every device but it'd be nice to
at
> least make this useful out of the box on one device class.
> 
> Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
> 
> otherwise
> 
> Cheers,
>    Peter
> 
> >
> >  	error = input_register_device(ts->input);
> >  	if (error) {
> > --
> > 2.7.4
> >