Re: [PATCH wireless] wifi: mac80211: use HT CCFS2 when computing the AP's HE and lower bandwidth

[Johannes Berg <johannes@sipsolutions.net>]

On Sun, 2026-10-25 at 21:01 -0700, John Macias wrote:
> If the driver advertises VHT extended NSS BW support, hostapd announces
> a 160 MHz BSS the way IEEE 802.11-2020 allows for that case: the VHT
> Operation element has channel width 1, CCFS0 is the 80 MHz segment and
> CCFS1 is 0, and the 160 MHz centre is in the CCFS2 field of the HT
> Operation element.
> 
> ieee80211_calc_ap_he_and_lower() only looks at the VHT CCFS1, so it
> sets bss_bw.he_and_lower to 80 MHz and ieee80211_sta_usable_bw() then
> limits every HE and VHT station to 80 MHz. Stations parse CCFS2 and use
> 160 MHz towards the AP, but the AP never transmits wider than 80 MHz.
> 
> Take CCFS2 from the HT Operation element when the VHT CCFS1 is 0, as
> the station side already does in ieee80211_chandef_vht_oper().

This, by itself, is wrong.

johannes