Re: [PATCH 3/3] input: mt: Move tracking and pointer emulation toinput-mt (rev2)

[Chris Bagwell]

On Mon, Dec 6, 2010 at 12:40 PM, Chase Douglas
<chase.douglas@xxxxxxxxxxxxx> wrote:
> On 12/01/2010 09:21 AM, Henrik Rydberg wrote:
>> The drivers using the type B protocol all report tracking information
>> the same way. The contact id is semantically equivalent to
>> ABS_MT_SLOT, and the handling of ABS_MT_TRACKING_ID only complicates
>> the driver. The situation can be improved upon by providing a common
>> pointer emulation code, thereby removing the need for the tracking id
>> in the driver.  This patch moves all tracking event handling over to
>> the input core, simplifying both the existing drivers and the ones
>> currently in preparation.
>
> When two or more fingers are down, one of the fingers controls
> ABS_{X,Y}. I think the aim is to emulate current behavior for
> synaptics-style touchpads, which average the position in firmware. Thus,
> we should be averaging the touch positions to generate the ABS_{X,Y} values.
>

At least for modern synaptics hardware, it does track to first touch
like this patch does.

It is maybe a weighted average were its 90% first finger and 10%
second finger.  Just moving second finger gives slight movement.

I can't really speak for other touchpad behavior.

Chris
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