[tslib] Setting ts_calibrate results EVIOCSABS

[Baruch Siach]

Hi Martin,

On Wed, Jun 21, 2017 at 09:05:37AM +0200, Martin Kepplinger wrote:
> On 2017-06-20 16:08, Baruch Siach wrote:
> > On Sun, Jun 18, 2017 at 04:45:15PM +0200, Martin Kepplinger wrote:
> >> On 2017-06-18 15:17, Baruch Siach wrote:
> >>> Is it possible to set the ts_calibrate results into the kernel input layer
> >>> using the EVIOCSABS ioctl()? That would make the calibration instantly
> >>> available to all touchscreen input device users, independent from the
> >>> tslib library.
> >>
> >> What version of tslib do you use? You should use a recent version from
> >> Debian sid, for example.
> >
> > I'm building the latest version statically using Buildroot.
> >
> >> Do you mean the ts_read_mt() tslib samples data? You might mainly use
> >> the linear plugin with ts_calibrate, but it's actually a special case.
> >> 
> >>> The problem I am facing is that I'm on X11, stuck with an old kernel (pre
> >>> of_touchscreen.c), and a Debian installation that does not package
> >>> xf86-input-tslib. The xf86-input-evdev Calibration option doesn't work at all
> >>> for some reason.
> >>
> >> Have you read the README.md documentation, specifically
> >> https://github.com/kergoth/tslib#use-the-filtered-result-in-your-system-ts_uinput-method
> >> ?
> >
> > Thanks for the pointer. I was not aware of that trick. I still think that
> > configuring the original input device is easier, since it doesn't require
> > special configuration on the Xorg side.
> 
> Well. Right. At least you have to tell Xorg to use the new "ts_uinput"
> device.
> 
> >> But xf86-input-tslib can also be installed seperately. It's indeed not
> >> yet packaged for Debian, but available here:
> >> https://github.com/merge/xf86-input-tslib
> >>
> >>> Looking around I could not find any EVIOCSABS user. The EVIOCSABS ioctl()
> >>> as been in the kernel since pre-git times.
> >>>
> >>> Am I missing something obvious here?
> >>
> >> Actually I don't know how common or useful it would be to edit the real
> >> device' values with EVIOCSABS. I always went the uinput way, creating a
> >> new device, until now.
> >>
> >> I'll think about it. Feel free to open an issue if you have a concrete idea.
> >
> > I found eventually that both systemd/udev and libevdev do EVIOCSABS.
> > systemd/udev could not help me because the version I have installed on target
> > is 215, while this feature was introduced only in 220 (commit 51c0c2869845a0).
> > So I settled for running the libevdev relatively new libevdev-tweak-device
> > utility from a custom udev rule. This solution works nicely.
> 
> How to read tslib's touch samples?
> 
> I may get it wrong, but if we add some daemon program that "tweaks"
> TSLIB_TSDEVICE, wouldn't tslib itself read that again and things would
> got wrong?

There is no daemon. libevdev-tweak-device calls the EVIOCSABS ioctl() only 
once when the device node is created.

> >>> FWIW, the touchscreen driver is edt-ft5x06.c, that works nicely except
> >>> from the calibration. Both X and Y are reported x2 at the X11 level.
> >>
> >> I have used this driver too. But it shouldn't matter at all.
> >
> > Thanks for your help,

baruch

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