[PATCH 12/23] wifi: mt76: mt7925: assign the interface WTBL to the NAN management TXQ

[Sean Wang <sean.wang@kernel.org>]

From: Jacobs Wu <jacobs.wu@mediatek.com>

mac80211 does not allocate vif->txq for a NAN device, so every SDF the
host sends - multicast discovery and unicast follow-up alike - is queued
on the dedicated management TXQ (vif->txq_mgmt) with txq->sta == NULL.

mt7925_mac_link_bss_add() only programs the wcid of vif->txq, so the
management TXQ keeps its initial wcid of 0. The mt76 TXQ scheduler then
resolves dev->wcid[0], i.e. the global WTBL, and every host-originated
SDF is transmitted on it. That WTBL only carries the parameters used for
beacons and has no usable unicast rate, so a unicast follow-up sent on it
is frequently not heard by the peer and the send is reported as failed.
Multicast SDFs are unaffected because they need no acknowledgment.

Program the management TXQ with the same interface WTBL that the beacon
and interface paths already use, which is fully initialised here.

Instrumenting the TX descriptor write shows every follow-up leaving on
WTBL 0 before the fix and on the interface WTBL after it; a 100-frame
unicast follow-up burst goes from 92-96 frames received to 100.

Fixes: 0f3605e4f8de ("wifi: mt76: mt7925: wire up NAN operations")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Jacobs Wu <jacobs.wu@mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7925/main.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/main.c b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
index 6c603d57e89f..64853fc7f60e 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
@@ -447,6 +447,17 @@ static int mt7925_mac_link_bss_add(struct mt792x_dev *dev,
 		mtxq->wcid = idx;
 	}
 
+	/* A NAN vif has no vif->txq; its SDFs are queued on vif->txq_mgmt,
+	 * whose wcid was never set and defaults to 0 (WTBL 0 has no unicast
+	 * rate), so unicast follow-ups go unacknowledged. Point txq_mgmt at
+	 * the same interface WTBL as the beacon path so SDFs continue to use
+	 * txq_mgmt but with a properly initialised wcid.
+	 */
+	if (vif->txq_mgmt) {
+		mtxq = (struct mt76_txq *)vif->txq_mgmt->drv_priv;
+		mtxq->wcid = idx;
+	}
+
 out:
 	return ret;
 }
-- 
2.43.0