[PATCH mt76-next 11/29] wifi: mt76: report data NSS for STBC frames in RX rate decode

[Felix Fietkau <nbd@nbd.name>]

The RX rate decoder set status->nss straight from the PRXV NSTS field,
which for STBC frames is twice the data spatial-stream count. cfg80211
then reported a doubled RX bitrate in station dumps and radiotap. Halve
nss for STBC, matching the TX status path.

Fixes: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Fixes: d832f5e73815 ("mt76: connac: move mt76_connac2_mac_fill_rx_rate in connac module")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c | 4 ++++
 drivers/net/wireless/mediatek/mt76/mt7996/mac.c      | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
index cbf6a987cf90..8a8d608dd56e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mac.c
@@ -1069,6 +1069,10 @@ int mt76_connac2_mac_fill_rx_rate(struct mt76_dev *dev,
 		bw = FIELD_GET(MT_CRXV_FRAME_MODE, v2);
 	}
 
+	/* the hardware reports NSTS; report the data NSS for STBC frames */
+	if (stbc && nss > 1)
+		nss >>= 1;
+
 	switch (*mode) {
 	case MT_PHY_TYPE_CCK:
 		cck = true;
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
index 866752f2fa24..4449dde33f4e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
@@ -294,6 +294,10 @@ mt7996_mac_fill_rx_rate(struct mt7996_dev *dev,
 	dcm = FIELD_GET(MT_PRXV_DCM, v2);
 	bw = FIELD_GET(MT_PRXV_FRAME_MODE, v2);
 
+	/* the hardware reports NSTS; report the data NSS for STBC frames */
+	if (stbc && nss > 1)
+		nss >>= 1;
+
 	switch (*mode) {
 	case MT_PHY_TYPE_CCK:
 		cck = true;
-- 
2.53.0