Re: [PATCH v3 7/7] Input: elantech - add v3 hardware support

[JJ Ding]

On Fri, 26 Aug 2011 09:28:13 -0500, Seth Forshee <seth.forshee@xxxxxxxxxxxxx> wrote:
> On Fri, Aug 26, 2011 at 09:03:11AM +0800, JJ Ding wrote:
> > +	/*
> > +	 * check debounce first, it has the same signature in byte 0 
> 
> Just one pedantic comment -- git complained about trailing whitespace on
> this line. Not that important, and Dmitry can clean it up when he
> applies the patch if he's so inclined.
> 
> This patch looks good now, and it's testing fine for me.
> 
> Reviewed-and-Tested-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
Thank you very much for viewing and testing this code, Seth.
> 
> I'm also curious what you found out about whether or not the touchpad
> does accurate finger tracking. I've played with it a little, and the
> finger tracking has been accurate except for one small exception. When
> the fingers are overlapping on one axis the touchpad always reports the
> same position for both fingers along that axis. For instance, if I move
> one finger up and the other finger down simultaneously on the touchpad,
> one of the fingers will show reverse movement on the y axis briefly
> while the fingers overlap. But I've never seen the fingers swap between
> the two frames of the packet.
I just got confirmed that with v3, two finger touch always gets reported
separately. I will resend this series for this update.
Add what you observed is actually hardware limitation. The v3 hardware
only has a projective sensor. When two fingers are overlapping along x or
y axis, the hardware can only sense one on that axis, once the two
fingers are away from the "crossing zone", they get reported separately again.

jj
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