From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH 2/2] input: mt: Document the MT event slot protocol (rev4)
Date: Mon, 24 May 2010 11:13:43 -0700
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To: Henrik Rydberg <rydberg@euromail.se>
Cc: Ping Cheng <pinglinux@gmail.com>, Randy Dunlap <rdunlap@xenotime.net>, Andrew Morton <akpm@linux-foundation.org>, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Mika Kuoppala <mika.kuoppala@nokia.com>, Peter Hutterer <peter.hutterer@who-t.net>, Benjamin Tissoires <tissoire@cena.fr>, Stephane Chatty <chatty@enac.fr>, Rafi Rubin <rafi@seas.upenn.edu>, Michael Poole <mdpoole@troilus.org>

On Mon, May 24, 2010 at 08:02:40PM +0200, Henrik Rydberg wrote:
> Ping Cheng wrote:
> > On Mon, May 24, 2010 at 12:13 AM, Henrik Rydberg <rydberg@euromail.se> wrote:
> >> Ping Cheng wrote:
> >>> What I am thinking is that we only need one SYN_ call for both _MT_
> >>> and regular data combined, which is a call to input_sync() at the end
> >>> of the whole packet. The SYN_MT_ can be replaced by the following
> >>> example, which I think is more "client-friendly". This solution is
> >>> based on the fact that the major difference between type A and type B
> >>> is whether we need to filter the data or not:
> >>>
> >>> ABS_MT_RANDOM 0
> >>> ABS_MT_POSITION_X x[0]
> >>> ABS_MT_POSITION_Y y[0]
> >>> ABS_MT_ RANDOM 1
> >>> ABS_MT_POSITION_X x[1]
> >>> ABS_MT_POSITION_Y y[1]
> >>> SYN_REPORT
> >>>
> >>> input_set_abs_params(input_dev, ABS_MT_RANDOM, 0, 2, 0, 0);
> >>>
> >>> would tell the clients that they can expect two random touches.
> >> And if you do s/RANDOM/SLOT/, you end up with what? ;-)
> > 
> > Haha, I know what you are thinking :).
> > 
> > Maybe I didn't make my point clear.  I didn't mean to make SLOT
> > backward compatible.  I meant to replace SYN_MT_REPORT event with the
> > ABS_MT_ RANDOM label so we only sync the whole packet once at the end.
> > This way both types of MT_ data follow the same input event reporting
> > flow....
> 
> You mean changing the type A protocol, breaking the current code base? That is a
> big no-no.
> 

We, however, could say that SYN_MT_REPORT may be omitted by the drivers
using slotting mechanism.

-- 
Dmitry