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Date:   Thu, 23 Feb 2017 00:45:31 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Sebastian Reichel <sre@...nel.org>
Cc:     "H. Nikolaus Schaller" <hns@...delico.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Cameron <jic23@...nel.org>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org
Subject: Re: [PATCH 2/3] Input: tsc2007 - correctly report pressure and not
 resistance to user space

On Tue, Feb 21, 2017 at 06:13:32PM +0100, Sebastian Reichel wrote:
> Hi,
> 
> On Mon, Feb 20, 2017 at 05:56:35PM +0100, H. Nikolaus Schaller wrote:
> > previously, tsc2007 will report as ABS_PRESSURE:
> > 0              for no pressure (resistance infinite)
> > high value     for soft pressure (high resistance)
> > low value      for firm pressure (lower resistance)
> > 
> > This does not matter for most applications (e.g. GUI, Menu, Scrolling
> > etc.) where the ABS_PRESSURE is ignored and only BTN_TOUCH is processed
> > to detect screen taps.
> > 
> > Only some special graphics applications read the pressure channel and
> > they will be mixed up by this non-monotonic relation.
> > 
> > So we fix it to become:
> > 0              for no pressure (resistance infinite)
> > low value      for soft pressure (high resistance)
> > high value     for firm pressure (lower resistance)
> > 
> > While this patch changes the values reported to userspace,
> > ABS_PRESSURE is used rarely by userspace. Most software only
> > relies on BTN_TOUCH (boolean), which is not affected by this
> > patch. Some graphics software makes use of the interface and
> > does not work correctly with the currently used inverted
> > behaviour.
> > 
> > Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> > ---
> >  drivers/input/touchscreen/tsc2007_core.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/input/touchscreen/tsc2007_core.c b/drivers/input/touchscreen/tsc2007_core.c
> > index 30b53ca..fc73849 100644
> > --- a/drivers/input/touchscreen/tsc2007_core.c
> > +++ b/drivers/input/touchscreen/tsc2007_core.c
> > @@ -141,6 +141,8 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
> >  				"DOWN point(%4d,%4d), resistance (%4u)\n",
> >  				tc.x, tc.y, rt);
> >  
> > +			rt = ts->max_rt - rt;
> > +
> >  			input_report_key(input, BTN_TOUCH, 1);
> >  			input_report_abs(input, ABS_X, tc.x);
> >  			input_report_abs(input, ABS_Y, tc.y);
> 
> Reviewed-By: Sebastian Reichel <sre@...nel.org>

Applied, thank you.

-- 
Dmitry

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