[PATCH v2 1/2] wifi: mt76: route TDLS-peer frames as 3-addr non-DS in HW encap

[ElXreno <elxreno@gmail.com>]

With HW TX encap offload enabled, the mt76 firmware builds the 802.11
header for the 802.3 frame using the per-WCID context. For a STATION
vif the HDR_TRANS TLV currently sets ToDS=1, which makes the firmware
default to the BSSID as A1 and emit STA->AP-formatted frames
regardless of which peer the WCID points to.

For TDLS-paired peers this is wrong. Data frames go on air addressed
to the AP, the AP MAC-ACKs and silently drops them per IEEE 802.11z
(an AP must not forward to a TDLS-paired peer). Management and
control frames bypass the HW encap path and still reach the peer;
only user data fails.

Add MT_WCID_FLAG_TDLS_PEER, set it in mt7915, mt7921, mt7925 and
mt7996 sta-add paths when sta->tdls is true, and override the
HDR_TRANS TLV in mt76_connac_mcu_wtbl_hdr_trans_tlv() (Connac2 -
mt7915 / mt7921 / mt7922), mt7925_mcu_sta_hdr_trans_tlv() (mt7925)
and mt7996_mcu_sta_hdr_trans_tlv() (mt7996) to set ToDS=0, FromDS=0
when the flag is set. The 3-addr non-DS form matches what 802.11z
uses for direct links; the firmware then constructs the frame with
A1=peer rather than A1=BSSID. HW encap offload remains enabled for
AP and any non-TDLS traffic.

Verified on mt7925e + Samsung S938B over a 5 GHz HE 80 MHz channel
with iperf3 -t 30 to the TDLS peer:

  before fix:  over the TDLS direct link, 7 TDLS Setup action
               frames and 3 RTS frames reach the peer; 0 QoS
               Data frames make it through (mgmt/control paths
               bypass HW encap, the data path does not). iperf3
               stalls.
  after fix:   2.90 GBytes transferred at 830 Mbit/s sustained,
               0 TCP retransmits.

mt7915, mt7921, mt7922 and mt7996 are not regression-tested in this
change for lack of hardware. Their HDR_TRANS handling mirrors the
verified mt7925 change; the firmware behavior is shared across these
chips.

Signed-off-by: ElXreno <elxreno@gmail.com>
Assisted-by: Claude:claude-opus-4-7 bpftrace tcpdump
---
 drivers/net/wireless/mediatek/mt76/mt76.h            | 1 +
 drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c | 5 +++++
 drivers/net/wireless/mediatek/mt76/mt7915/main.c     | 3 +++
 drivers/net/wireless/mediatek/mt76/mt7921/main.c     | 3 +++
 drivers/net/wireless/mediatek/mt76/mt7925/main.c     | 3 +++
 drivers/net/wireless/mediatek/mt76/mt7925/mcu.c      | 5 +++++
 drivers/net/wireless/mediatek/mt76/mt7996/main.c     | 3 +++
 drivers/net/wireless/mediatek/mt76/mt7996/mcu.c      | 5 +++++
 8 files changed, 28 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 527bef97e122..07955555f84d 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -361,6 +361,7 @@ enum mt76_wcid_flags {
 	MT_WCID_FLAG_PS,
 	MT_WCID_FLAG_4ADDR,
 	MT_WCID_FLAG_HDR_TRANS,
+	MT_WCID_FLAG_TDLS_PEER,
 };
 
 #define MT76_N_WCIDS 1088
diff --git a/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c b/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
index 89bd52ea8bf7..f61d0625ef51 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76_connac_mcu.c
@@ -491,6 +491,11 @@ void mt76_connac_mcu_wtbl_hdr_trans_tlv(struct sk_buff *skb,
 		htr->to_ds = true;
 		htr->from_ds = true;
 	}
+
+	if (test_bit(MT_WCID_FLAG_TDLS_PEER, &wcid->flags)) {
+		htr->to_ds = false;
+		htr->from_ds = false;
+	}
 }
 EXPORT_SYMBOL_GPL(mt76_connac_mcu_wtbl_hdr_trans_tlv);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/main.c b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
index e1d83052aa6d..51643a48ed15 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/main.c
@@ -760,6 +760,9 @@ int mt7915_mac_sta_add(struct mt76_dev *mdev, struct ieee80211_vif *vif,
 	msta->wcid.phy_idx = ext_phy;
 	msta->jiffies = jiffies;
 
+	if (sta->tdls)
+		set_bit(MT_WCID_FLAG_TDLS_PEER, &msta->wcid.flags);
+
 	ewma_avg_signal_init(&msta->avg_ack_signal);
 
 	mt7915_mac_wtbl_update(dev, idx,
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/main.c b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
index 3d74fabe7408..d39cb881d75e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/main.c
@@ -828,6 +828,9 @@ int mt7921_mac_sta_add(struct mt76_dev *mdev, struct ieee80211_vif *vif,
 	msta->deflink.last_txs = jiffies;
 	msta->deflink.sta = msta;
 
+	if (sta->tdls)
+		set_bit(MT_WCID_FLAG_TDLS_PEER, &msta->deflink.wcid.flags);
+
 	ret = mt76_connac_pm_wake(&dev->mphy, &dev->pm);
 	if (ret)
 		return ret;
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/main.c b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
index 73d3722739d0..61330e3c18b2 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
@@ -887,6 +887,9 @@ static int mt7925_mac_link_sta_add(struct mt76_dev *mdev,
 	mlink->wcid.link_valid = !!link_sta->sta->valid_links;
 	mlink->sta = msta;
 
+	if (link_sta->sta->tdls)
+		set_bit(MT_WCID_FLAG_TDLS_PEER, &mlink->wcid.flags);
+
 	wcid = &mlink->wcid;
 	ewma_signal_init(&wcid->rssi);
 	rcu_assign_pointer(dev->mt76.wcid[wcid->idx], wcid);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
index 22bad3cba8df..333cacfaca9c 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/mcu.c
@@ -1091,6 +1091,11 @@ mt7925_mcu_sta_hdr_trans_tlv(struct sk_buff *skb,
 		hdr_trans->to_ds = true;
 		hdr_trans->from_ds = true;
 	}
+
+	if (test_bit(MT_WCID_FLAG_TDLS_PEER, &wcid->flags)) {
+		hdr_trans->to_ds = false;
+		hdr_trans->from_ds = false;
+	}
 }
 
 int mt7925_mcu_wtbl_update_hdr_trans(struct mt792x_dev *dev,
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/main.c b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
index a8a6552d49f6..9b8db6efb5ac 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
@@ -1164,6 +1164,9 @@ mt7996_mac_sta_init_link(struct mt7996_dev *dev,
 	msta_link->wcid.link_valid = !!sta->valid_links;
 	msta_link->wcid.def_wcid = &msta->deflink.wcid;
 
+	if (link_sta->sta->tdls)
+		set_bit(MT_WCID_FLAG_TDLS_PEER, &msta_link->wcid.flags);
+
 	ewma_avg_signal_init(&msta_link->avg_ack_signal);
 	ewma_signal_init(&msta_link->wcid.rssi);
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
index 16420375112d..6aaf3ed94221 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mcu.c
@@ -2139,6 +2139,11 @@ mt7996_mcu_sta_hdr_trans_tlv(struct mt7996_dev *dev, struct sk_buff *skb,
 		hdr_trans->from_ds = true;
 		hdr_trans->mesh = true;
 	}
+
+	if (test_bit(MT_WCID_FLAG_TDLS_PEER, &wcid->flags)) {
+		hdr_trans->to_ds = false;
+		hdr_trans->from_ds = false;
+	}
 }
 
 static enum mcu_mmps_mode

-- 
2.53.0