5Ghz WiFi blocked by vc4.ko on kernel 5.10.12 on RPi4B 8GB

Ryutaroh Matsumoto ryutaroh at ict.e.titech.ac.jp
Wed Feb 3 01:18:43 EST 2021

> * I am able to connect my 2.4 GHz WiFi, while I am unable to connect 5 GHz.
> * My HDMI output is 3840x2160 at 30 Hz.

"ping" packets do not reach to another host on 2.4 GHz WiFi,
while NetworkManager or systemd-networkd connects to SSID of 2.4GHz.
For 5GHz with vc4.ko, NetworkManager does not connect to the SSID of 5GHz,
so the symptom is better with 2.4GHz.
The symptom of 2.4GHz is the same both with vc4 and without vc4.

"iw dev wlan0 info" prints as follows, but ping packets do not reach.
Interface wlan0
	ifindex 3
	wdev 0x1
	addr dc:a6:32:bb:99:da
	ssid *****
	type managed
	wiphy 0
	channel 4 (2427 MHz), width: 20 MHz, center1: 2427 MHz
	txpower 31.00 dBm

The only usable configuration is WiFi 5GHz connection with module_blacklist=vc4...

Best regards, Ryutaroh

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