Digi Embedded Linux 5.9 default Linux build for ConnectCard (Wi-)i.MX28 by default has not configured any graphical capabilities.
In order to run the Qt example applications with the Fusion 7" LCD as used in the i.MX28 Android kit, you have to enable the following features in your Linux project (Kernel + RootFS + Applications):
In device drivers -> Input decive support, select Event Interface: INPUT_EVDEV
in same section select Touchscreens: INPUT_TOUCHSCREEN
under Touchscreens select Fusion 7/10 multi-touch TOUCHSCREEN_FUSION_7_10
In Device Drivers -> Graphics support enable Support for frame buffer devices: FB
In System Type -> Freescale i.MXS implementations Video Options
Enable support for the Fusion 7/10 multi-touchscreen on JSK: CCWMX28_FUSION_7_10_MULTITOUCH
In System Type -> Freescale Application UART, disable Application UART 1: MXS_UART1_DEVICE_ENABLE
In Application Configuration select Application Template -> tetrix_qt: APPS_TETRIX_QT
In Rootfs Configuration Pre-built applications select Qt for Emb. Linux example apps: DEL_PACKAGE_QT_EMBEDDED
Make sure you have Jumper P66 "Touch Screen" set (for Android its not needed but) for Linux! Its under the LCD, so you have to unscrew LCD (bottom side of JSK board), set jumper and re-screw LCD.
In U-Boot make sure you have appropriate "video" variable set to: displayfb:LCD@F07A0102. This should already be set if Android was running before.
Build and Install the project and deploy kernel and rootfs to the module (e.g. update linux;update rootfs; after partions are setup for Linux with flpart). Boot Linux, e.g. dboot linux flash, or dboot linux tftp and edit file /etc/profile.d/touchscreen.sh and modify ts0 into event0. Reboot or exectue this file to add appropriate Linux environment variables.
Launch the calibration tool:
touch the crosshairs to calibrate the touch
or any other /usr/bin/qt-embedded/* -qws to launch application.
Optionally you might want to enable back light control and Linux boot logo, in the project configuration under Device Drivers->Graphics near the frame buffer settings.