wifi: mt76: support upgrading passive scans to active

On channels with NO_IR or RADAR flags, wait for beacon before sending
probe requests. Allows active scanning and WPS on restricted channels
if another AP is already present.

Fixes: c56d6edebc1f ("wifi: mt76: mt7996: use emulated hardware scan support")
Tested-by: Piotr Kubik <piotr.kubik@adtran.com>
Signed-off-by: Chad Monroe <chad@monroe.io>
Link: https://patch.msgid.link/20251118102723.47997-2-nbd@nbd.name
Link: https://patch.msgid.link/20260309060730.87840-2-nbd@nbd.name
Signed-off-by: Felix Fietkau <nbd@nbd.name>

4 files changed, 56 insertions, 3 deletions

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index d0c522909e98..3c539c263238 100644
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -726,6 +726,7 @@ mt76_alloc_device(struct device *pdev, unsigned int size,
 	INIT_LIST_HEAD(&dev->rxwi_cache);
 	dev->token_size = dev->drv->token_size;
 	INIT_DELAYED_WORK(&dev->scan_work, mt76_scan_work);
+	spin_lock_init(&dev->scan_lock);
 
 	for (i = 0; i < ARRAY_SIZE(dev->q_rx); i++)
 		skb_queue_head_init(&dev->rx_skb[i]);
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 23a1832812a2..ffeb4b4c425b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -1003,6 +1003,7 @@ struct mt76_dev {
 	u32 rxfilter;
 
 	struct delayed_work scan_work;
+	spinlock_t scan_lock;
 	struct {
 		struct cfg80211_scan_request *req;
 		struct ieee80211_channel *chan;
@@ -1010,6 +1011,8 @@ struct mt76_dev {
 		struct mt76_vif_link *mlink;
 		struct mt76_phy *phy;
 		int chan_idx;
+		bool beacon_wait;
+		bool beacon_received;
 	} scan;
 
 #ifdef CONFIG_NL80211_TESTMODE
@@ -1597,6 +1600,7 @@ int mt76_get_rate(struct mt76_dev *dev,
 int mt76_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		 struct ieee80211_scan_request *hw_req);
 void mt76_cancel_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif);
+void mt76_scan_rx_beacon(struct mt76_dev *dev, struct ieee80211_channel *chan);
 void mt76_sw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		  const u8 *mac);
 void mt76_sw_scan_complete(struct ieee80211_hw *hw,
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
index be70c0f4fc30..f5537eba9c6b 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
@@ -515,6 +515,9 @@ mt7996_mac_fill_rx(struct mt7996_dev *dev, enum mt76_rxq_id q,
 		qos_ctl = FIELD_GET(MT_RXD10_QOS_CTL, v2);
 		seq_ctrl = FIELD_GET(MT_RXD10_SEQ_CTRL, v2);
 
+		if (ieee80211_is_beacon(fc))
+			mt76_scan_rx_beacon(&dev->mt76, mphy->chandef.chan);
+
 		rxd += 4;
 		if ((u8 *)rxd - skb->data >= skb->len)
 			return -EINVAL;
diff --git a/drivers/net/wireless/mediatek/mt76/scan.c b/drivers/net/wireless/mediatek/mt76/scan.c
index 89f16c23e352..2b5f30cef795 100644
--- a/drivers/net/wireless/mediatek/mt76/scan.c
+++ b/drivers/net/wireless/mediatek/mt76/scan.c
@@ -27,6 +27,10 @@ static void mt76_scan_complete(struct mt76_dev *dev, bool abort)
 
 void mt76_abort_scan(struct mt76_dev *dev)
 {
+	spin_lock_bh(&dev->scan_lock);
+	dev->scan.beacon_wait = false;
+	spin_unlock_bh(&dev->scan_lock);
+
 	cancel_delayed_work_sync(&dev->scan_work);
 	mt76_scan_complete(dev, true);
 }
@@ -79,6 +83,28 @@ out:
 	rcu_read_unlock();
 }
 
+void mt76_scan_rx_beacon(struct mt76_dev *dev, struct ieee80211_channel *chan)
+{
+	struct mt76_phy *phy;
+
+	spin_lock(&dev->scan_lock);
+
+	if (!dev->scan.beacon_wait || dev->scan.beacon_received ||
+	    dev->scan.chan != chan)
+		goto out;
+
+	phy = dev->scan.phy;
+	if (!phy)
+		goto out;
+
+	dev->scan.beacon_received = true;
+	ieee80211_queue_delayed_work(phy->hw, &dev->scan_work, 0);
+
+out:
+	spin_unlock(&dev->scan_lock);
+}
+EXPORT_SYMBOL_GPL(mt76_scan_rx_beacon);
+
 void mt76_scan_work(struct work_struct *work)
 {
 	struct mt76_dev *dev = container_of(work, struct mt76_dev,
@@ -87,9 +113,20 @@ void mt76_scan_work(struct work_struct *work)
 	struct cfg80211_chan_def chandef = {};
 	struct mt76_phy *phy = dev->scan.phy;
 	int duration = HZ / 9; /* ~110 ms */
-	bool offchannel = true;
+	bool beacon_rx, offchannel = true;
 	int i;
 
+	if (!phy || !req)
+		return;
+
+	spin_lock_bh(&dev->scan_lock);
+	beacon_rx = dev->scan.beacon_wait && dev->scan.beacon_received;
+	dev->scan.beacon_wait = false;
+	spin_unlock_bh(&dev->scan_lock);
+
+	if (beacon_rx)
+		goto probe;
+
 	if (dev->scan.chan_idx >= req->n_channels) {
 		mt76_scan_complete(dev, false);
 		return;
@@ -110,10 +147,18 @@ void mt76_scan_work(struct work_struct *work)
 
 	mt76_set_channel(phy, &chandef, offchannel);
 
-	if (!req->n_ssids ||
-	    chandef.chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))
+	if (!req->n_ssids)
 		goto out;
 
+	if (chandef.chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) {
+		spin_lock_bh(&dev->scan_lock);
+		dev->scan.beacon_received = false;
+		dev->scan.beacon_wait = true;
+		spin_unlock_bh(&dev->scan_lock);
+		goto out;
+	}
+
+probe:
 	if (phy->offchannel)
 		duration = HZ / 16; /* ~60 ms */
 	local_bh_disable();