Re: [PATCH] input-mt: Allow -1 for tracking id

[Sadrul Chowdhury <sadrul@chromium.org>]

On Fri, Apr 15, 2011 at 3:00 AM, Henrik Rydberg <rydberg@euromail.se> wrote:
> Hi Sadrul,
>
> On Thu, Apr 14, 2011 at 06:13:17PM -0400, Sadrul Chowdhury wrote:
>> In protocol B, the tracking ID can be set to -1. But since the min
>> value is set to 0, the clients don't receive a -1 when a contact is
>> lifted. The attached patch sets the min to -1 to fix this issue.
>
> All ABS_MT_TRACKING_ID values outside the valid value range denote an
> invalid touch. To simplify implementation in userland, where the valid
> range may not always be known, the documentation was changed to say
> "-1" instead. Apparently the original explanation was unintentionally
> dropped with it.
>
> Because the change goes against the semantics of the tracking id, this
> patch constitues an interface breakage, with malfunctions in userspace
> as a result. Therefore, this patch will not be applied.

Ah, that makes sense. Thanks for the explanation. I will fix things on
the client end.

Thanks.
Sadrul