linux-kernel - Re: ads7846 touchscreen: fix pressure

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Message-ID: <20091009163506.GE1092@core.coreip.homeip.net>
Date:	Fri, 9 Oct 2009 09:35:07 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Trilok Soni <soni.trilok@...il.com>, linux-input@...r.kernel.org,
	kernel list <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: ads7846 touchscreen: fix pressure

On Thu, Oct 08, 2009 at 11:24:33AM +0200, Pavel Machek wrote:
> On Thu 2009-10-08 10:39:39, Trilok Soni wrote:
> > Hi Pavel,
> > 
> > On Wed, Oct 7, 2009 at 1:24 AM, Pavel Machek <pavel@....cz> wrote:
> > >
> > > On Zaurus, pressure is reported inverted -- the lighter the pressure,
> > > the bigger numerical value. This should fix it.
> > >
> > > Signed-off-by: Pavel Machek <pavel@....cz>
> > >
> > > --- linux-rc/drivers/input.ofic/touchscreen/ads7846.c   2009-10-06 13:49:56.000000000 +0200
> > > +++ linux-rc/drivers/input/touchscreen/ads7846.c        2009-10-06 21:18:25.000000000 +0200
> > > @@ -608,12 +609,12 @@
> > >
> > >                input_report_abs(input, ABS_X, x);
> > >                input_report_abs(input, ABS_Y, y);
> > > -               input_report_abs(input, ABS_PRESSURE, Rt);
> > > +               input_report_abs(input, ABS_PRESSURE, ts->pressure_max-Rt);
> > 
> > but same behavior is seen by others using this chip on different
> > boards? If not, this has to be done through platform data.
> 
> Well, I'd expect the chip to behave in similar way on all
> platforms. Of course, it would be good if someone with different hw
> tested it, but I do not have that hw...
> 
> So I guess the best way is to make it go in early and see how it does
> in testing....

No, this is not how it works. Please do

	git log -- drivers/input/touchscreen/ads7846.c

and try to check with people who were working on this driver. I somehow
doubt that they'd overlook such obvious issue as inverted pressure
readings.

-- 
Dmitry
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