[PATCH] wifi: mac80211: mlme: allow VHT/HE connections for 20MHz BW STAs

[PATCH] wifi: mac80211: mlme: allow VHT/HE connections for 20MHz BW STAs

[Sabeeh Khan]

The ieee80211_determine_our_sta_mode function assumes that
if a radio supports VHT and is limited to 20MHz BW,
then it must be limited to use HT connection.

This is incorrect by spec as VHT/HE connections can still
be allowed. Specify VHT connection and then goto current
checks for HE capable and flag.

Signed-off-by: Sabeeh Khan <sabeeh-khan@ti.com>
---
 net/mac80211/mlme.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index f51167f0fc46..eed6294f4c65 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -6586,8 +6586,9 @@ ieee80211_determine_our_sta_mode(struct ieee80211_sub_if_data *sdata,
 
 		if (conn->bw_limit == IEEE80211_CONN_BW_LIMIT_20) {
 			mlme_link_id_dbg(sdata, link_id,
-					 "no 40 MHz support on 5 GHz, limiting to HT\n");
-			goto out;
+					 "no 40 MHz support on 5 GHz\n");
+			conn->mode = IEEE80211_CONN_MODE_VHT;
+			goto conn_band_5ghz_vht_bw_20;
 		}
 
 		/* Allow VHT if at least one channel on the sband supports 80 MHz */
@@ -6626,6 +6627,7 @@ ieee80211_determine_our_sta_mode(struct ieee80211_sub_if_data *sdata,
 				 "no VHT 160 MHz capability on 5 GHz, limiting to 80 MHz");
 	}
 
+conn_band_5ghz_vht_bw_20:
 	if (req && req->flags & ASSOC_REQ_DISABLE_HE) {
 		mlme_link_id_dbg(sdata, link_id,
 				 "HE disabled by flag, limiting to HT/VHT\n");
-- 
2.34.1

Re: [PATCH] wifi: mac80211: mlme: allow VHT/HE connections for 20MHz BW STAs

[Johannes Berg]

On Fri, 2026-08-28 at 13:25 -0500, Sabeeh Khan wrote:
> The ieee80211_determine_our_sta_mode function assumes that
> if a radio supports VHT and is limited to 20MHz BW,
> then it must be limited to use HT connection.
> 
> This is incorrect by spec as VHT/HE connections can still
> be allowed.

... Which already says why your patch is incorrect.

I have a real patch for this issue somewhere though, like this:
https://p.sipsolutions.net/a5d970acf354f0ef.txt

We/I should send it soon.

johannes

Re: [PATCH] wifi: mac80211: mlme: allow VHT/HE connections for 20MHz BW STAs

[Khan, Sabeeh]

On 9/3/2026 12:05 PM, Johannes Berg wrote:
> On Fri, 2026-08-28 at 13:25 -0500, Sabeeh Khan wrote:
>> The ieee80211_determine_our_sta_mode function assumes that
>> if a radio supports VHT and is limited to 20MHz BW,
>> then it must be limited to use HT connection.
>>
>> This is incorrect by spec as VHT/HE connections can still
>> be allowed.
> ... Which already says why your patch is incorrect.
>
> I have a real patch for this issue somewhere though, like this:
> https://p.sipsolutions.net/a5d970acf354f0ef.txt
>
> We/I should send it soon.
>
> johannes
Thank you for the review Johannes, and I will wait for your patch.