We have encountered an issue on an embedded device (RZ/G2E running Linux Yocto) which runs a Qt 6.5.3 application on EGLFS, mirroring video output over HDMI to an external monitor. 

When the HDMI cable is connected before the device boots, the video output works at the expected resolution. However, if the HDMI cable is unplugged and then reconnected after the Qt application has already launched, the external monitor no longer receives the correct EDID data and thus does not display at the expected resolution.

Our investigation suggests that EDID information (including supported resolutions and vendor data) is not being transmitted properly once the Qt app has started. This problem only appears if the cable is reconnected after the Qt application is up and running.

Would you have any known cases or recommendations on how to resolve this kind of HDMI EDID transmission issue, specifically when Qt is handling DRM or display initialization on the embedded device?

Any guidance or insights would be greatly appreciated.