On Tue, 2022-10-18 at 10:13 +0530, Rameshkumar Sundaram wrote:
> Stations can update bandwidth/NSS change in
> VHT action frame with action type Operating Mode Notification.
> (IEEE Std 802.11-2020 - 9.4.1.53 Operating Mode field)
>
> For Operating Mode Notification, an RX NSS change to a value
> greater than AP's maximum NSS should not be allowed.
> Hence allow NSS change only up to maximum NSS that is negotiated
> and capped to AP's capability during association.
That seems reasonable. Might be worth noting in a comment in the code
which AP has such bugs though, just so we know it later.
> if (link_sta->pub->rx_nss != nss) {
> - link_sta->pub->rx_nss = nss;
> - sta_opmode.rx_nss = nss;
> - changed |= IEEE80211_RC_NSS_CHANGED;
> - sta_opmode.changed |= STA_OPMODE_N_SS_CHANGED;
> + cur_nss = link_sta->pub->rx_nss;
> + link_sta->pub->rx_nss = 0;
> + ieee80211_sta_set_rx_nss(link_sta);
> + /* Do not allow an nss change to rx_nss greater than max_nss
> + * negotiated and capped to APs capability during association.
> + */
> + if (nss <= link_sta->pub->rx_nss) {
> + link_sta->pub->rx_nss = nss;
That, however, doesn't seem right. It means that you can only ever
reduce the RX NSS, not switch it around within the originally negotiated
range.
johannes
