Re: [PATCH 2/2] input: mt: Document the MT event slot protocol (rev3)

From: Dmitry Torokhov
Date: Fri May 21 2010 - 13:41:52 EST

On Fri, May 21, 2010 at 07:29:39PM +0200, Henrik Rydberg wrote:
> Dmitry Torokhov wrote:
> > On Fri, May 21, 2010 at 06:56:35PM +0200, Henrik Rydberg wrote:
> >> Dmitry Torokhov wrote:
> >>> On Friday 21 May 2010 09:36:03 am Henrik Rydberg wrote:
> >>>> Ping Cheng wrote:
> >>>>> Hi Henrik,
> >>>>>
> >>>>> Thank you for your quick turnaround. Two minor comments in line.
> >>>>>
> >>>>> Ping
> >>>> Thanks for those, yes, both mistakes. Dmitry, in case you find these last
> >>>> versions acceptable, perhaps one could change them manually:
> >>>>
> >>>> 1. Patch description: s/SYN_MT_SLOT/ABS_SLOT/
> >>> Not ABS_MT_SLOT?
> >> I wrote an argument for ABS_SLOT in the first patch, in short there is a
> >> namespace clash I would like to avoid.
> >>
> >
> > Hm, I am not sure I follow that argument. While you are saying that slot
> > is not an MT event it is certainly not an ST event either. I would even
> > say that slot _is_ an MT event since it signals current "slot" or group
> > of MT data to userspace. Am I missing something?
> >
> It is really a SYN or control event, since it sets which slot is currently being
> updated. However, as argued earlier in this thread, since the presence and value
> range of the slot variable is needed in user space, converting it to an ABS
> event makes sense. But ABS_SLOT is not a property of the slot, and is thus not
> an MT event in that respect. Currently, all ABS_MT events are either bypassing
> filtering altogether, or (with these patches) being routed via a slot. The
> naming convention ABS_MT is the only clue to user space that this is event will
> appear once per slot. I think it should remain that way.

I guess this is where our disconnect lies as when I am looking at the
event names I view all *_MT_* events as related to the multitouch
protocol handling.

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