Is this the HDMI of your AMD GPU from the other thread, or the HDMI that's built into the motherboard?
I'm a little confused by your wording of reloading vs standby vs switch.
However, I think you're describing an issue I've had before with AMD cards. Let's see if I understand:
- You turn off the computer using the power supply switch
- You turn it back on and boot, you can see output on the AMD card
- You "reboot" (computer goes back to bootloader, but the lights don't go out)
- You don't see output in the AMD card this time
It is unclear if we share this part, but this also happens for me:
- You turn on the computer and you see bootloader on AMD card
- You "shutdown" (don't flip switch, but the lights go out until you press power button again)
- You turn it back on and boot
- You should see bootloader (I did)
Basically, powering off the GPU entirely makes it work. It's a bug in AMD GPUs that doesn't have a perfect software workaround yet. My current workaround is to disable fast reboots so all reboots turn into "shutdown, then power on". You can do this by running the following command in the bootloader shell:
nvram -p ibm,skiboot --update-config fast-reset=0