我在 Raspberry PI 4 上安装了 Ubuntu 桌面。令我惊讶的是，HDMI-CEC 无法正常工作。这是一个已知的错误吗？
$ sudo apt-get install cec-utils libcec-dev
$ cec-client -l
LibCEC version: 6.0.2 compiled on Linux-4.15.0-109-generic ... , features: P8_USB, DRM, p8_detect, randr, Exynos, AOCEC
Found devices: NONE
Ubuntu 版本：
$ lsb_release -a
Distributor ID: Ubuntu
Description: Ubuntu 20.10
Release: 20.10
Codename: groovy
$ uname -a
Linux <redacted-user> 5.8.0-1007-raspi #10-Ubuntu SMP PREEMPT Thus Nov 5 17:52:40 UTC 2020 aarch64 aarch64 GNU/Linux