Editor's note: this article was originally written focused on VLX, but the general concept applies to VLX and VPX products.
If you have used a Raspberry Pi with a VLX, you may have noticed that the VLX will always switch to the Pi as the active input when it reboots, even if auto-sense is disabled. This happens because the Raspberry Pi sends the HDMI CEC command "Active Source" on startup. This command is received by the VLX, which causes the switch.
To disable the CEC switch command on the Raspberry Pi, the following configuration can be modified:
Add hdmi_ignore_cec=1 to /boot/config.txt
Originally published 2/10/2021