[PATCH 16/23] wifi: mt76: mt7925: double the retry budget for NAN unicast management

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

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

The NAN setup handshakes are one-shot at the host: wpa_supplicant aborts
PASN on the first unacknowledged authentication frame and completes the
NDP state machine without retransmitting an unacknowledged key-install.
Right after the data path confirm both peers transmit at each other
nearly simultaneously, and with half-duplex radios one 15-retry burst
regularly dies inside the peer's own TX window (measured ~50% loss of
the key-install on an MT7925 pair, killing the NDP setup).

Double the TXD retry budget to the field maximum for NAN unicast
management so the burst outlives the cross-fire window.

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/mac.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
index 101f571b027f..f19d0451f373 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/mac.c
@@ -806,6 +806,19 @@ mt7925_mac_write_txwi(struct mt76_dev *dev, __le32 *txwi,
 
 	val = FIELD_PREP(MT_TXD3_REM_TX_COUNT, 15);
 
+	/* NAN setup handshakes are one-shot at the host: a single lost burst
+	 * kills the NDP (peers transmit at each other nearly simultaneously
+	 * after M3 and half-duplex radios miss the reply). Double the retry
+	 * budget so the burst outlives the cross-fire window.
+	 */
+	if (vif && vif->type == NL80211_IFTYPE_NAN) {
+		struct ieee80211_hdr *nan_hdr = (struct ieee80211_hdr *)skb->data;
+
+		if (ieee80211_is_mgmt(nan_hdr->frame_control) &&
+		    !is_multicast_ether_addr(nan_hdr->addr1))
+			val = FIELD_PREP(MT_TXD3_REM_TX_COUNT, 31);
+	}
+
 	if (key)
 		val |= MT_TXD3_PROTECT_FRAME;
 	if (info->flags & IEEE80211_TX_CTL_NO_ACK)
-- 
2.43.0