Re: [PATCH v1] xen/input: add multi-touch support

[Oleksandr Andrushchenko]

Hi, Dmitry!

On 06/29/2017 10:24 PM, Dmitry Torokhov wrote:
> On June 29, 2017 11:40:30 AM PDT, Oleksandr Andrushchenko <andr2000@xxxxxxxxx> wrote:
> > Hi, Dmitry!
> >
> > First of all thank you for both the comments and the patch
> >
> > On 06/29/2017 11:17 AM, Dmitry Torokhov wrote:
> > > Hi Oleksandr,
> > >
> > > On Fri, Jun 23, 2017 at 09:09:55AM +0300, Oleksandr Andrushchenko
> > wrote:
> > > > +			switch (event->mtouch.event_type) {
> > > > +			case XENKBD_MT_EV_DOWN:
> > > > +				input_mt_report_slot_state(dev, MT_TOOL_FINGER,
> > > > +							   true);
> > > > +				input_event(dev, EV_ABS, ABS_MT_POSITION_X,
> > > > +					    event->mtouch.u.pos.abs_x);
> > > > +				input_event(dev, EV_ABS, ABS_MT_POSITION_Y,
> > > > +					    event->mtouch.u.pos.abs_y);
> > > > +				input_event(dev, EV_ABS, ABS_X,
> > > > +					    event->mtouch.u.pos.abs_x);
> > > > +				input_event(dev, EV_ABS, ABS_Y,
> > > > +					    event->mtouch.u.pos.abs_y);
> > > I was looking at this and realized that this breaks the single touch
> > > emulation for MT interface: for ST you are supposed to report the
> > oldest
> > > contact, here you report data for all of them. Luckily
> > > input_mt_report_pointer_emulation() that is called as part of
> > > input_mt_sync_frame() reports the correct ABS_X/ABS_Y data and fixes
> > > that for you.
> > >
> > > We should simply remove reporting ABS_X/ABS_Y here and in
> > > XENKBD_MT_EV_MOTION as well.
> > >
> > > > +
> > > > +		input_set_capability(mtouch, EV_KEY, BTN_TOUCH);
> > > > +		input_set_abs_params(mtouch, ABS_X,
> > > > +				     0, width, 0, 0);
> > > > +		input_set_abs_params(mtouch, ABS_Y,
> > > > +				     0, height, 0, 0);
> > > > +		input_set_abs_params(mtouch, ABS_PRESSURE,
> > > > +				     0, 255, 0, 0);
> > > This is done automatically by input_mt_init_slots() when called with
> > > INPUT_MT_DIRECT (as in your case) or INPUT_MT_POINTER, so this can be
> > > removed as well.
> > Great, I was not actually convinced that ABS is really needed
> > to be put here while dealing with MT devices,
> > so the above can be removed
> > > Does the patch below (on top of yours) work for you?
> > Unfortunately I didn't have time to test the patch today, but will try
> > to do so tomorrow.
> >
> > Beside that, do you think that the removals above should go into my
> > patch
> > and the rest of yours (it looks like needed refactoring to me) should
> > go
> > into
> > a separate one, not named "MT support fixups", but rather "Xen input
> > driver refactoring"? Because part of the changes seems to be MT
> > relevant
> > and part is pure refactoring.
> > If so, do you want me to rework your patch with these changes and add
> > on
> > top of mine (I will put your signed off) or you will handle it on your
> > own?
> I was planning on simply folding my changes into your patch and calling it a day, unless your testing would show there is an issue.
I found no issue with the patches, but I have only tested that
on ARM with our new kbd/ptr/mt backend [1]. I am not able to test that
on x86 unfortunately, thus cannot confirm QEMU's backend is ok as well.
What will be the next steps on my side to get MT in?
>   It wasn't intended to be a separate patch in it's own right, I simply sent it out this way to show what exactly I was changing.
>
>
> Thanks.
Thank you,
Oleksandr

[1] https://github.com/xen-troops/displ_be