Bug 14206

Summary:	Kodi: even when not enabled, forcefully selects libevdev and libinput [was: QT5 touch screen rotation does not work since 2021.05]
Product:	buildroot	Reporter:	Thomas Ruschival <t.ruschival>
Component:	Other	Assignee:	Yann E. MORIN <yann.morin.1998>
Status:	RESOLVED FIXED
Severity:	normal	CC:	buildroot, yann.morin.1998
Priority:	P5
Version:	2021.05
Target Milestone:	---
Hardware:	All
OS:	Linux
Host:		Target:
Build:

Description Thomas Ruschival 2021-09-06 13:29:48 UTC

The `rotate` parameter for the touchscreen orientation does not work using environment variable QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS in QT5. e.g.
QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS=/dev/input/touch:rotate=90 has no effect.
No value for rotation (90,180,270) has any effect.

It used to work up until 2021.02 and stopped working since Buildroot 2021.05.

Looking for the cause I found that since 2021.05 libxkbcommon (BR2_PACKAGE_LIBXKBCOMMON) and libinput (BR2_PACKAGE_LIBINPUT) are selected. In turn libevdev (BR2_PACKAGE_LIBEVDEV) is selected.
Libinput and libxkbcommon are selected by BR2_PACKAGE_KODI_PLATFORM_SUPPORTS_GBM.

As a quick check I removed the line 'source "package/kodi/Config.in"' form
package/Config.in and rebuilt all in this case the touch-input rotation works.

Kodi was never selected on the system.  Would it make sense to only select
libinput and libxkbcommon if BR2_PACKAGE_KODI is actually selected?

I guess this affects all applications using QT5 with a rotated touch screen - can anyone confirm this issue?

Comment 1 Thomas Ruschival 2021-09-08 12:30:44 UTC

I succeeded narrowing down the issue by commenting out "package/kodi/Config.in"' in package/Config.in and manually adding libraries.

Adding only libevdev does not affect the behavior of QT. Adding libinput as well the touch screen rotation does no longer work.

Apparently /usr/lib/qt/plugins/platforms/libqeglfs.so is dynamically linked against libinput if it is available during build time of Qt5.

Comment 2 Thomas Ruschival 2021-09-10 11:55:41 UTC

It is not a bug but a behavior of Qt5 v5.15.
(https://doc.qt.io/qt-5/inputs-linux-device.html) 

The issue can be solved/worked around in two different ways:

Either: 
Disable the use of libinput (QT_QPA_EGLFS_NO_LIBINPUT=1) and continue using the environment variable QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS=/dev/input/touch:rotate=90

OR: 
use the generic platform plugin configuration variable QT_QPA_GENERIC_PLUGINS=evdevtouch:/dev/input/touch:rotate=90

Comment 3 Yann E. MORIN 2021-09-11 07:59:08 UTC

Thomas, All,

(In reply to Thomas Ruschival from comment #0)
> Looking for the cause I found that since 2021.05 libxkbcommon (BR2_PACKAGE_LIBXKBCOMMON)
> and libinput (BR2_PACKAGE_LIBINPUT) are selected. In turn libevdev (BR2_PACKAGE_LIBEVDEV)
> is selected.
> Libinput and libxkbcommon are selected by BR2_PACKAGE_KODI_PLATFORM_SUPPORTS_GBM.

Indeed, this code is incorrect; good catch! :-)

I'll send a patch soonish to fix that.

Regards,
Yann E. MORIN.

Comment 4 Yann E. MORIN 2021-09-17 21:30:49 UTC

Thomas, All,

Thanks for the report. We believe the issue has now been fixed with commit
b80c488d04 (package/kodi: fix selection of dependencies).

Regards,
Yann E. MORIN.