Raspberry Pi 4 Compute module 4 CM4 no Wifi with Ubuntu 20.04 server

Solution 1:

Problem

My student research group had this issue after flashing RPi/CM4 with Ubuntu Server 20.04 LTS; when running ls /sys/class/net and sudo hwinfo --network --short only eth0 and lo exists.

Problem solving

We ran dmesg | grep -i sdio and discovered an error regarding failed to load driver for Wi-Fi chipset (image).

When checking the drivers installed, by running ls /lib/firmware/brcm/ , there were two drivers missing (image):

brcmfmac43455-sdio.txt

brcmfmac43455-sdio.raspberrypi,4-compute-module.txt

Solution

note: be aware of the difference between 43455 and 43456.

1. We found the first driver on github: https://github.com/RPi-Distro/firmware-nonfree/blob/master/brcm/brcmfmac43455-sdio.txt

Just download it in the folder using

sudo wget https://raw.githubusercontent.com/RPi-Distro/firmware-nonfree/master/brcm/brcmfmac43455-sdio.txt

2. For the second driver we did not find anything, however, we compared the the following drivers:

brcmfmac43456-sdio.raspberrypi,4-compute-module.txt

brcmfmac43456-sdio.raspberrypi,4-model-b.txt

and discovered they where identical. Just duplicate the brcmfmac43455-sdio.raspberrypi,4-model-b.txt and rename it to brcmfmac43456-sdio.raspberrypi,4-compute-module.txt.

After reboot Wi-Fi works!

Distro issue? We believe this may be a distro-issue..