Re: [PATCH 2/2]input - wacom_w8001: Add one finger touch support

[Chris Bagwell <chris@cnpbagwell.com>]

On Fri, Dec 10, 2010 at 1:38 AM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> On Thu, Dec 09, 2010 at 03:21:34PM -0600, Chris Bagwell wrote:
>>
>> For first point, your right that (123,78) is just a good "known
>> starting value" if a driver is going to use that concept because it
>> could be filtered just as easy as (0,0).
>
> I am afraid I did not explain myself well enough. (0,0) is valid
> coordinate, same as (123, 78). Thus, even if we try to make driver send
> (0,0, !touch), input core may suppress it and never deliver to
> userspace if last touching point happened to be also (0,0). Thus
> userspace should not rely on having coordinates reset I think.
>

I had understood ya.  What I meant is if a driver sends (0,0,!touch)
and a sync when switching tools then you do not need to buffer
previous values but instead can imply what previous values are.
Userland would still need to account for case of filtered events.  Its
a memset() vs. a memcpy() when switching tools.

Anyways,  I'm not recommending any behavior; just letting you know
some existing assumptions on driver behavior.

Thanks,
Chris