[tslib] Setting ts_calibrate results EVIOCSABS

[Martin Kepplinger]

On 2017-06-20 16:08, Baruch Siach wrote:
> Hi Martin,
>
> 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?

>
>>> 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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