The Linux kernel (v5.4.0) used in Ubuntu 20.04 has poor support for the HDMI sound support—the sound device shows “Dummy Output” after every computer sleep. I had tried different solutions but still would like to forget about running those commands before getting the sound out. So, I upgraded the kernel to the latest version supported by Ubuntu and it works. Below is the list of commands that I used.
$ wget https://raw.githubusercontent.com/pimlie/ubuntu-mainline-kernel.sh/master/ubuntu-mainline-kernel.sh $ sudo install ubuntu-mainline-kernel.sh /usr/local/bin/ $ sudo ubuntu-mainline-kernel.sh -i Finding latest version available on kernel.ubuntu.com Latest version is: v5.7.0, continue? (y/N) $ sudo update-grub $ sudo grub-customizer
Since I used grub-customizer to manage Grub options, I also ran the last two commands to add the new kernel to boot options in Grub. After reboot the computer with the new kernel, I no longer have the “Dummy Output” issue any more.