vcgencmd not working with linux-raspberrypi4 on aarch64

[unformatted]

On RPi4 I installed AArch64 and replaced linux-aarch64 with linux-raspberrypi4 kernel. However vcgencmd gives the following error:

$this->bbcode_second_pass_code('', '
[user@PC19 ~]$ /opt/vc/bin/vcgencmd measure_temp
VCHI initialization failed
')

Here's my configuration:

$this->bbcode_second_pass_code('', '
[user@PC19 ~]$ uname -a
Linux PC19 5.10.63-14-ARCH #1 SMP PREEMPT Wed Sep 29 07:54:37 UTC 2021 aarch64 GNU/Linux

[user@PC19 ~]$ pacman -Qs raspberry
local/firmware-raspberrypi 20210224-1
Additional firmware for Raspberry Pi
local/linux-raspberrypi4 5.10.63-14
The Linux Kernel and modules - Raspberry Pi 3/4/400
local/raspberrypi-bootloader 20210928-2
Bootloader files for Raspberry Pi
local/raspberrypi-bootloader-x 20210928-2
Bootloader with extra codecs for Raspberry Pi
local/raspberrypi-firmware 20210928-2
Firmware tools, libraries, and headers for Raspberry Pi

[user@PC19 ~]$ cat /boot/config.txt
# See /boot/overlays/README for all available options
initramfs initramfs-linux.img followkernel
temp_limit=70
hdmi_blanking=1
dtoverlay=disable-wifi
dtoverlay=disable-bt

[user@PC19 ~]$ cat /boot/cmdline.txt
root=/dev/mmcblk0p2 rw rootwait console=serial0,115200 console=tty1 selinux=0 plymouth.enable=0 smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 kgdboc=serial0,115200

[user@PC19 ~]$ groups
users wheel
')

Now the groups are interesting. If I add my user to the video group then vcgencmd works. However, on my other RPi4's which are currently running ARMv7 the user is also only member of users and wheel group and vcgencmd is working. Why is that? What is different between ARMv7 installation and AArch64 installation with swapped kernels?

[graysky]

I believe you need to be the video group as pointed out. Can't remember why.