Hi, there is one way to fix the hdmi output in default resolution, maybe you can try it.
find the dts file then modify it as below:
hdcp_onoff = <0>;
channel_invert = <0>;
bit_invert = <0>;
hotplugable = <0>;
bootable = <1>;
bootrotate = <0>;
default_resolution = "1280x720p-60";
if only modify hdmi default_resolution were not fixed HDMI output resolution,
maybe you can also disable EDID funciton.
i2c_num = <3>;
clock-frequency = <400000>;
status = "disabled";
pinctrl-names = "default";
pinctrl-0 = <&i2c3_state_over_spi0>;
try it hope you can get the results you want.