By the way, how to make sure that the update occured?
Code
LibreELEC5:~ # grep . /sys/module/vc4/parameters/*
/sys/module/vc4/parameters/cec_debug:256
/sys/module/vc4/parameters/fkms_max_refresh_rate:85
/sys/module/vc4/parameters/inval_delay:0
/sys/module/vc4/parameters/tv_norm:(null)
If you are not running the correct version, then you won't see the cec_debug/inval_delay entries.
And the values shown should match what you added to cmdline.txt