linux-kernel - Re: [PATCH 3/3] Input: synaptics - remove touches over button click area

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Message-ID: <4CB34F53.6080409@euromail.se>
Date:	Mon, 11 Oct 2010 19:54:27 +0200
From:	Henrik Rydberg <rydberg@...omail.se>
To:	Chris Bagwell <chris@...bagwell.com>
CC:	Takashi Iwai <tiwai@...e.de>,
	Chase Douglas <chase.douglas@...onical.com>,
	linux-input@...r.kernel.org, xorg-devel@...ts.x.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Andy Whitcroft <apw@...onical.com>,
	linux-kernel@...r.kernel.org,
	Peter Hutterer <peter.hutterer@...-t.net>,
	Duncan McGreggor <duncan.mcgreggor@...onical.com>
Subject: Re: [PATCH 3/3] Input: synaptics - remove touches over button click
 area

On 10/11/2010 07:46 PM, Chris Bagwell wrote:
[...]

>>> I'm convinced now that clickpad style touchpads can't work without
>>> multi-touch and something like logic in xf86-input-multitouch.
>>
>> Actually Clickpad works without multi-touch patch.  With my patches to
>> synaptics, it worked in some level.  There are many restrictions (e.g.
>> pushing the button first then drag), though.
>>
> 
> True, but if I understand synaptic hardware MT behavior (sends
> actively moving finger in higher resolution packet regardless of
> original finger touch) then your patch will result in jumpy cursor on
> X side and that side would need patches to attempt to guess invalid
> data and discard.  I've worked on a few similar patches to various
> xf86-input-* and generally they've failed to detect difference between
> invalid packets vs. fast user movements.
> 
> The main point of my 3 options was to address jumpy cursor in
> xf86-input-* that are not MT aware.  I think ABS_X/ABS_Y should only
> allow its meaning to change at detectable time periods so user can
> account for it and, specifically, that time period is best at
> transition of BTN_TOOL_DOUBLETAP.
> 
> Assuming its easy enough to support exact rules for ABS_X/ABS_Y
> changing meanings on kernel side (which I think it probably is pretty
> easy), I think we should do it so that applications don't have to
> become MT-aware as the official solution for jumpy cursors.


A solution like the one you describe was actually proposed and agreed upon in
the beginning of this thread, so I think the only thing left to do is actually
write the patch. :-) I can only assume that Takashi or Chase will be back in a
bit with an update.

Cheers,
Henrik
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