linux-kernel - Re: [PATCH 2/2] Input: tsc2007 - Add a z1_low

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Date:	Wed, 30 Nov 2011 21:47:26 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Feng Tang <feng.tang@...el.com>
Cc:	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Clark, Joel" <joel.clark@...el.com>
Subject: Re: [PATCH 2/2] Input: tsc2007 - Add a z1_low_threshhold platform
 data parameter

On Wed, Nov 30, 2011 at 10:34:18AM +0800, Feng Tang wrote:
> On Tue, 29 Nov 2011 17:23:10 +0800
> Dmitry Torokhov <dmitry.torokhov@...il.com> wrote:
> 
> > On Tue, Nov 29, 2011 at 04:12:58PM +0800, Feng Tang wrote:
> > > This originates from a patch in Meego IVI kernel with the name
> > > 	linux-2.6.37-connext-0027-tsc2007.patch
> > > There is no author info excepte a line "From  MeeGo
> > > <kernel@...go.com>"
> > > 
> > > When integrating tsc2007 on Intel IVI platform, there are a lot of
> > > noise data whose z1 value is around 10 which is not a sane "z1". So
> > > add a "z1_low_threshhold" to filter those nosie data, to make the
> > > device work properly.
> > 
> > Sounds like a task for userspace to ignore pressure that is too low.
> > Bonus points for making it configurable so user can adjust
> > sensitivity.
> 
> Actually, there is one more point :), without this patch, the driver won't
> work on our platforms.
> 
> The tsc2007_soft_irq will keep reading the input data unless there is no
> valid pressure data. In our case, those noise data will be seen as valid
> data during tsc2007_calculate_pressure(), and the tsc2007_soft_irq will
> run endlessly.

Even if we add the pressure threshold would not that noise cause endless
stream of interrupts?

Also, what kind of z2 is reported with low z1? And do you implement
get_pendown_state()?

Thanks.

-- 
Dmitry
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