Qt 5.15.12 Creating GBM device for file descriptor is very slow

Astraya

Hello,

I have a raspberry pi 3B+ with latest bookworm on it.
The first time the application start after a fresh boot, the line Creating GBM device for file descriptor 7 obtained from "/dev/dri/card0"is very slow the first time ( approximately 2 or 3 seconds if not more ). But if i restart the application, it start directly with no latency. I imagine that there is some cache that is created...
I whould like to know if there is a possiblity to avoid the discovering of the device or pre-create the GBM device for file descriptor. The hardware will never change after a deployment.

Here is the debugs:

Got keys from plugin meta data ("eglfs_kms")
QFactoryLoader::QFactoryLoader() checking directory path "/root/ihm/egldeviceintegrations" ...
loaded library "/usr/local/qt5.15.10/plugins/egldeviceintegrations/libqeglfs-kms-integration.so"
qt.qpa.eglfs.kms: New DRM/KMS via GBM integration created
qt.qpa.eglfs.kms: platformInit: Opening DRM device
qt.qpa.eglfs.kms: Found the following video devices: ("/dev/dri/card0")
qt.qpa.eglfs.kms: Using "/dev/dri/card0"
qt.qpa.eglfs.kms: Using backend-provided DRM device /dev/dri/card0
qt.qpa.eglfs.kms: Creating GBM device for file descriptor 7 obtained from "/dev/dri/card0"
qt.qpa.eglfs.kms: Using dedicated drm event reading thread
qt.qpa.eglfs.kms: Initalizing event reader for device 0x6e09a0 fd 7
qt.qpa.eglfs.kms: Querying EGLDisplay
qt.qpa.eglfs.kms: Event reader thread: entering event loop

Here is how i start it

TSLIB_TSDEVICE=/dev/input/ts_raw \
TSLIB_CONFFILE=/etc/ts.conf \
QT_QPA_EGLFS_NO_LIBINPUT=1 \
QT_QPA_EGLFS_TSLIB=1 \
QT_QPA_GENERIC_PLUGINS=evdevtouch:/dev/input/ts_raw \
QT_LOGGING_RULES=qt.qpa.eglfs.kms=true \
QT_QPA_EGLFS_KMS_CONFIG=gbm.json \
QT_QPA_EGLFS_KMS_ATOMIC=1 \
QT_QPA_EGLFS_KMS_PLANE_INDEX=0 ./my_app -platform eglfs -plugin tslib

Content of the gbm.json:

{
  "device": "/dev/dri/card0",
  "outputs": [
    {
      "name": "HDMI1",
      "mode": "1024x600"
    }
  ]
}

Thank you

diana658h

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