For my Pi Zero and Pi Zero W, I bought many mini HDMI (to HDMI) cables from various vendors in order to find one working with the CEC feature, with no success.
Unfortunately, only my mini-HDMI to HDMI small adapter, with a regular HDMI cable, appears to work.
I noticed another strange behavior : with a Pi Zero W, I randomly have some visual glitches and even blank screens with the mini-HDMI to HDMI adapter and regular cable. I haven't those glitches and blank screens with any of my mini-HDMI cables, the image is stable and perfect, but I lose the CEC feature using them.
Here are my test conditions :
- Tested with a Samsung TV supporting CEC (Anynet+).
- Tested with 2 Pi Zero W and 1 standard Pi Zero (last version, with CSI). All of them have exactly the same behavior.
- Tested with LibreElec 8.0.2 and 8.2.1 (same SD with all Pi Zero).
- Tested with 2 different power sources (on the TV USB and a regular 5V 2A power supply).
- Tested with an USB key containing movies and without (to eliminate power consumption issue).
- Tested without other HDMI devices connected (read that it can cause conflicts)
The CEC feature works very well with my Pi 2 running LibreElec (and other Pi with regular HDMI plug).
I tried to tweak the config.txt in order to boost HDMI signal with not a single effect on the issue.
I bought mini HDMI cables certified to work with CEC (ARC, ethernet, and so on) with no results.