From: Ulf Brosziewski <ulf.brosziewski@t-online.de>
Subject: Re: Help with backport support of Apple MagicTracpad 2
To: "Kirill A. Korinsky" <kirill@korins.ky>, tech@openbsd.org
Date: Tue, 5 Mar 2024 16:13:47 +0100

If you manage to activate raw mode, the next problem you might encounter
is that ubcmtp won't work if it configures wsmouse without the
WSMOUSEHW_MT_TRACKING flag.

ubcmtp uses wsmouse_mtframe() for passing inputs to wsmouse, and this
function has been added to wsmouse for the (rare) case that MT hardware
doesn't provide tracking data - or that the relevant details of the
protocol are unknown.

wsmouse_mtframe() does nothing if the MT_TRACKING flag isn't set.

However, it seems that Magic Trackpads do provide tracking IDs - in the
'id' field of the 'ubcmtp_finger_compact' struct.  You could map these
IDs to slot values with wsmouse_id_to_slot, and apply the "normal" method
of reporting MT inputs to wsmouse, that is, by calling wsmouse_mtstate as
long as a touch is active, and signalling its end by calling the function
with a 'pressure' value of 0.

And, just in case you are puzzled by the terminology:  A "tracking ID"
is an arbitrary number that identifies a touch within a series of input
reports.  By "slots", I refer to IDs that are restricted to the range [0-n],
where n is small enough for using the values as array indices.  In the
current implementation, the maximal number of MT slots in wsmouse is 10,
which is reason why the 'id_to_slot' mapping would be necessary even for
4-bit IDs.

BTW, if you send further diffs to tech@, please send them inline (and
make sure that your mail client doesn't reformat them).


On 3/3/24 22:57, Kirill A. Korinsky wrote:
> Dear tech@,
> 
> I need help with backporting support of Apple MagicTracpad 2.
> 
> As a base implementation I've used code from FreeBSD [1] which seems quite
> trivial.
> 
> Anyway, a naive reimplementation doesn't work. When I attach the device I
> have inside dmesg:
> 
>   uhidev0 at uhub0 port 1 configuration 1 interface 0 "Apple Inc. Magic Trackpad" rev 2.00/8.60 addr 4
>   uhidev0: iclass 3/0, 224 report ids
>   uhid0 at uhidev0 reportid 144: input=2, output=0, feature=0
>   uhid1 at uhidev0 reportid 154: input=1, output=0, feature=0
>   uhid2 at uhidev0 reportid 224: input=4, output=0, feature=0
>   ubcmtp0 at uhub0 port 1 configuration 1 interface 1 "Apple Inc. Magic Trackpad" rev 2.00/8.60 addr 4
>   ubcmtp0: attached to 0x5ac/0x265 type 5
>   wsmouse4 at ubcmtp0
>   ubcmtp0: ubcmtp_raw_mode: failed to toggle raw mode
>   ubcmtp0: failed to enter raw mode
>    attach error=1
>   uhidev1 at uhub0 port 1 configuration 1 interface 3 "Apple Inc. Magic Trackpad" rev 2.00/8.60 addr 4
>   uhidev1: iclass 3/0, 192 report ids
>   uhid3 at uhidev1 reportid 192: input=107, output=0, feature=0
>   uhid0 detached
>   uhid1 detached
>   uhid2 detached
>   uhidev0 detached
>   wsmouse4 detached
>   ubcmtp0 detached
>   uhid3 detached
>   uhidev1 detached
> 
> that means that it can't enter into raw mode.
> 
> So, I deffently had missed something.
> 
> 
> Footnotes:
> [1]  https://github.com/freebsd/freebsd-src/commit/ef8397c28e981e0115d435aabcf57cee7ea5f5ee
>