linux-kernel - Re: [PATCH 02/12] Input: synaptics

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Date:	Tue, 5 Jul 2011 13:39:13 -0500
From:	Chris Bagwell <chris@...bagwell.com>
To:	Henrik Rydberg <rydberg@...omail.se>
Cc:	Daniel Kurtz <djkurtz@...omium.org>, dmitry.torokhov@...il.com,
	chase.douglas@...onical.com, rubini@...l.unipv.it,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	derek.foreman@...labora.co.uk, daniel.stone@...labora.co.uk,
	olofj@...omium.org
Subject: Re: [PATCH 02/12] Input: synaptics - do not invert y if 0

On Tue, Jul 5, 2011 at 1:07 PM, Henrik Rydberg <rydberg@...omail.se> wrote:
>> > > In some cases, however, y = 0 is sent by the touchpad.
>> > > In these cases, the kernel driver should not invert, and just report 0.
>> > >
>> > > This patch also refactors the inversion into a macro, and moves it
>> > > into packet processing instead of during position reporting.
>> >
>> > The patch seems to invert the current output?
>>
>> By 'current' do you mean referenced from the previous implementation?
>> Or referenced from the raw input.
>> It does indeed invert the raw input.
>> This is the same as the previous implementation did.
>> The difference is that it does not also invert the special 'y=0' into
>> an arbitrarily large value.
>> Is this your concern?
>
> It would be clearer to just change the argument of the
> input_report_abs() instances, would it not? An explanation why zero,
> outside the value range, should be output also needs a rationale. It
> would seem such packets should be masked somehow.
>

When I saw this, thats what it looked like to me.  We already know
that hw.x == 1 is invalid and added to a list to filter out but maybe
hw.y == 0 is invalid as well and it wasn't as obvious because of the
inversion.

Sound the following pre-existing line be expanded to its filtered?

       if (hw.z > 0 && hw.x > 1) {

Chris
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