Touchscreen calibration matrix changes

[Teemu K]

Persistent storage was never the problem. Issue was getting the
non-default values in use, but it has now been sorted.

-TeemuK

On Wed, Apr 6, 2022 at 7:58 AM Peter Hutterer <peter.hutterer at who-t.net> wrote:
>
> On Wed, Apr 06, 2022 at 06:02:22AM +0300, Teemu K wrote:
> > On Tue, Apr 5, 2022 at 5:21 PM Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > >
> > > On Tue, 29 Mar 2022 15:31:59 +0300
> > > Teemu K <maillinglists18 at gmail.com> wrote:
> > >
> > > > Hi,
> > > >
> > > > I'm trying to get touch calibration working on Wayland/Weston for
> > > > resistive touch. I can get the calibration points and calculate
> > > > calibration matrix values, but when I call
> > > > libinput_device_config_calibration_set_matrix and then read it back it
> > > > would seem that the matrix is changed, but the actual touchscreen does
> > > > not indicate so. Ie. if I calibrate the touch clearly wrong it still
> > > > behaves like it would have been calibrated perfectly.
> > >
> > > Hi,
> > >
> > > what exactly do you mean by "when I call
> > > libinput_device_config_calibration_set_matrix", what is "I" there?
> > By "I" I mean the application.
> >
> > > > If I set the same values to udev rule like this:
> > > > ATTRS{name}=="tsc2007", ENV{LIBINPUT_CALIBRATION_MATRIX}="1.29342,
> > > > -0.0223598, -0.135092, -0.0272545, -1.11435, 1.04368"
> > > >
> > > > They get taken in use and I can read those values as default values
> > > > with libinput_device_config_calibration_get_default_matrix - function.
> > >
> > > That's right.
> > >
> > > > Is there something else that needs to be done to get the updated
> > > > matrix taken in use or is there known issue with Wayland/Weston given
> > > > that it is quite old version Wayland 1.17.0/Weston 6.0.1.
> > > > Unfortunately I'm stuck with those versions for now.
> > >
> > > I'm not sure what problem you have. The udev rule works, right?
> > Yeah, but the problem was replacing those defaults with the calibrated
> > values with that ibinput_device_config_calibration_set_matrix -
> > function.
> >
> > > Or do you mean updating the calibration matrix while Weston is already
> > > running?
> > >
> > > Did you write a new program that simply calls
> > > libinput_device_config_calibration_set_matrix() and then expect Weston
> > > to pick that up when you run it?
> > Weston is already running and I'm trying to set a new matrix in use
> > for Weston. Is that not what the
> > ibinput_device_config_calibration_set_matrix - function is meant for?
> >
> > > If so, then libinput just does not work that way. There is no persistent
> > > configuration in libinput, and any setting you make is local in the
> > > in-memory libinput data structure. The udev rules are the persistent
> > > configuration. That's why e.g. calibration_helper option exists in
> > > weston.ini, so that you could have your own way of storing the
> > > calibration in udev rules.
> > This is not the issue. I'm very well aware that there is no persistent
> > storage in libinput and I'm not trying to use it as such. I'm trying
> > to set a new matrix when Weston is already running.
>
> The issue here is less whether libinput has persistent storage, the issue is
> that you do not have access to the libinput context that the compositor uses.
> https://wayland.freedesktop.org/libinput/doc/latest/faqs.html#can-i-write-a-program-to-make-libinput-do-foo
>
> The only way around this is to use compositor-provided knobs that *the
> compositor* then converts into libinput configuration calls. Like the weston
> touch protocol that you have found now.
>
> Cheers,
>   Peter
>
> >
> > But I ended up copying the implementation from weston-touch-calibrator
> > as you mentioned instead and it worked so this issue is solved.
> >
> > Thanks.
> >
> > -TeemuK
> >
> > > It looks like clients/touch-calibrator.c existed already in Weston
> > > 6.0.0. It's a ready-made calibration tool that computes
> > > LIBINPUT_CALIBRATION_MATRIX values, and uploads those to Weston. You
> > > need weston.ini option touchscreen_calibrator=true to make it work, and
> > > the calibration_helper option to save the calibration persistent. These
> > > are described in the weston.ini man page, and there is an example
> > > script at
> > > https://gitlab.freedesktop.org/wayland/weston/-/blob/main/doc/scripts/calibration-helper.bash
> > >
> > > The option touchscreen_calibrator=true exposes a Wayland extension that
> > > allows both getting raw touch coordinates and uploading a new
> > > calibration matrix to Weston. This is the only way to update the matrix
> > > without restarting Weston.
> > >
> > >
> > > Thanks,
> > > pq