Re: Dell Latitude E7470 touchpad status

[Ben Gamari <ben@smart-cactus.org>]

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Pali Rohár <pali.rohar@gmail.com> writes:

> On Wednesday 25 May 2016 14:32:28 Ben Gamari wrote:
>> 
>> The first attached patch gets me partly there; I see multitouch events,
>> the pressure appears to reflect reality, and things generally work as
>> expected. That is, until I try to touch the touchstick, which causes the
>> pointer to jump around wildly.
>
> So with first patch touchpad starts working fine and just trackstick
> cause problems?
>
> Reason for non working trackstick is simple. Driver alps.c does not
> support trackstick in V8 protocol. So you even does not see second
> (trackstick) input device, right?
>
Correct.

>> The second attached patch makes things behave slightly better,
>
> Looking at the alps.c code it should act exactly same. V8 does not
> support trackpoint, so ALPS_DUALPOINT has no effect. There should not be
> any difference between your first and second patch. Can you play more
> and confirm it?
>
Ahh, so you are right. I apparently misread the code.

>> but the touchstick still does not work as expected. Settting
>> ALPS_PS2_INTERLEAVED as well doesn't appear to change anything.
>
> ALPS_PS2_INTERLEAVED is just for V2 protocol. It does not have any
> effect for other protocols.
>
Good to know. It would be nice if there were a comment indicating this
in alps.c.

>> Ideas?
>
> I think now we just need description of trackstick format for V8
> protocol. And then implement it in alps V8 parser.
>
Lovely. I'd be happy to carry out the implementation if protocol
documentation is available.

Cheers,

- Ben

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