MT7921u: Driver doesn't support chan-switch with channel contexts (please help test this...)

[ea4eoz]

Hello!

After using a Comfast CF-953AX for about 10 days I noticed disconnections from time to time.

Looking into syslog I found for every disconnection this:

kernel: driver doesn't support chan-switch with channel contexts wpa_supplicant: CTRL-EVENT-DISCONNECTED bssid=a6:64:xx:xx:xx:xx reason=4 locally_generated=1

After a quick search in the kernel tree, this happens when the AP issues a frequency / channel change because of DFS (using 802.11h: IEEE80211_HW_CHANCTX_STA_CSA) and the kernel driver does not handle it. The action in response is to disconnect the link.

So... in the current status of MT7921u driver is it does not handle DFS issues, so expect frequent link disconnections while working in the 5 GHz band. Keep it in mind if you need a rock solid connection to your AP.

Probably this must be added to the known issues list, because it can be a no-go for many users.

Tested using Debian Sid with kernel 6.3.7