Hello, I'm using an MT7921 PCIe card in AP mode on the 5GHz band. It works well when I manually set a channel in hostapd.conf. Setting channel=0 or channel=acs_survey (both have the same meaning) should make hostapd check for a suitable channel and pick that automatically. Unfortunately this does not work as hostapd reports the following (for all frequencies/channels): ACS: Survey for freq 5180 is missing noise floor ACS: Survey for freq 5180 is missing noise floor ACS: Survey for freq 5180 is missing noise floor ACS: Survey for freq 5180 is missing noise floor ACS: Survey for freq 5180 is missing noise floor ACS: Channel 36 has insufficient survey data I suspect that this is due to mt792x_phy_update_channel() (from drivers/net/wireless/mediatek/mt76/mt792x_mac.c) which calls mt792x_phy_get_nf(). The latter just returns zero - so it seems reading the noise floor from the hardware/firmware is not supported yet. What is needed to implement this? I can test patches or - if someone describes which registers to program - I can also write a patch and submit it upstream. Thank you and best regards, Martin