Here comes our internal team’s suggeston as your reference:
This appears to be due to the built-in timeouts in CBoot - you can see in the video that it waits 2 seconds (autoboot timeout) for input to enter the CBoot shell, then after reading in extlinux.conf, it waits 3 seconds based on the TIMEOUT 30 entry in extlinux.conf. So if they want to speed this up, i.e. always skip the shell and always boot the first entry in extlinux.conf w/o waiting for input, then they can:
Modify the public CBoot source for T19x to remove CONFIG_ENABLE_SHELL from the rules.mk/l4t.mk config files and rebuild & reflash their new CBoot (copy lk.bin to cboot_t194.bin in their BSPs ‘bootloader’ subdir). That should get rid of the autoboot timeout.
Modify their eMMC extlinux.conf (/boot/extlinux/extlinux.conf) to set the TIMEOUT parameter to 1, or remove it. IIRC, that should skip any delay and process the first menu entry right away.
Together that should shave off 5-6 seconds of boot delay before you see the splash screen (which happens in CBoot right before kernel boot, so one of the last things it does).
I did remove CONFIG_ENABLE_SHELL, and also dont wait on TIMEOUT in extlinux.conf. The issue is even I display boot BMP early, it can’t be shown on screen. Looks like DP/eDP display is not ready to show BMP on screen.