mt76: mt7615: fix reading airtime statistics

- change the WTBL LMAC access function to set the mapping window only once
- use ac * 2 as offset, since each AC has separate words for rx and tx
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/mac.c

@@ -88,13 +88,12 @@ bool mt7915_mac_wtbl_update(struct mt7915_dev *dev, int idx, u32 mask)
 			 0, 5000);
 }
 
-static u32 mt7915_mac_wtbl_lmac_read(struct mt7915_dev *dev, u16 wcid,
-				     u16 addr)
+static u32 mt7915_mac_wtbl_lmac_addr(struct mt7915_dev *dev, u16 wcid)
 {
 	mt76_wr(dev, MT_WTBLON_TOP_WDUCR,
 		FIELD_PREP(MT_WTBLON_TOP_WDUCR_GROUP, (wcid >> 7)));
 
-	return mt76_rr(dev, MT_WTBL_LMAC_OFFS(wcid, addr));
+	return MT_WTBL_LMAC_OFFS(wcid, 0);
 }
 
 /* TODO: use txfree airtime info to avoid runtime accessing in the long run */
@@ -121,6 +120,7 @@ void mt7915_mac_sta_poll(struct mt7915_dev *dev)
 
 	while (true) {
 		bool clear = false;
+		u32 addr;
 		u16 idx;
 
 		spin_lock_bh(&dev->sta_poll_lock);
@@ -133,20 +133,23 @@ void mt7915_mac_sta_poll(struct mt7915_dev *dev)
 		list_del_init(&msta->poll_list);
 		spin_unlock_bh(&dev->sta_poll_lock);
 
-		for (i = 0, idx = msta->wcid.idx; i < IEEE80211_NUM_ACS; i++) {
+		idx = msta->wcid.idx;
+		addr = mt7915_mac_wtbl_lmac_addr(dev, idx) + 20 * 4;
+
+		for (i = 0; i < IEEE80211_NUM_ACS; i++) {
 			u32 tx_last = msta->airtime_ac[i];
-			u32 rx_last = msta->airtime_ac[i + IEEE80211_NUM_ACS];
+			u32 rx_last = msta->airtime_ac[i + 4];
+
+			msta->airtime_ac[i] = mt76_rr(dev, addr);
+			msta->airtime_ac[i + 4] = mt76_rr(dev, addr + 4);
 
-			msta->airtime_ac[i] =
-				mt7915_mac_wtbl_lmac_read(dev, idx, 20 + i);
-			msta->airtime_ac[i + IEEE80211_NUM_ACS] =
-				mt7915_mac_wtbl_lmac_read(dev, idx, 21 + i);
 			tx_time[i] = msta->airtime_ac[i] - tx_last;
-			rx_time[i] = msta->airtime_ac[i + IEEE80211_NUM_ACS] -
-				     rx_last;
+			rx_time[i] = msta->airtime_ac[i + 4] - rx_last;
 
 			if ((tx_last | rx_last) & BIT(30))
 				clear = true;
+
+			addr += 8;
 		}
 
 		if (clear) {