wifi: mt76: mt7921: fix antenna signal are way off in monitor mode

Group 3 in RxD is disabled in monitor mode. We should use the group 5 in
RxD instead to fix antenna signal way off issue, e.g we would see the
incorrect antenna signal value in wireshark. On the other hand, Group 5
wouldn't be used in STA or AP mode, so the patch shouldn't cause any
harm to those modes.

Fixes: cbaa0a40 ("mt76: mt7921: fix up the monitor mode")
Reported-by: Adrian Granados <agranados@gmail.com>
Co-developed-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7921/mac.c

@@ -396,6 +396,27 @@ mt7921_mac_fill_rx(struct mt7921_dev *dev, struct sk_buff *skb)
 		if (v0 & MT_PRXV_HT_AD_CODE)
 			status->enc_flags |= RX_ENC_FLAG_LDPC;
 
+		ret = mt76_connac2_mac_fill_rx_rate(&dev->mt76, status, sband,
+						    rxv, &mode);
+		if (ret < 0)
+			return ret;
+
+		if (rxd1 & MT_RXD1_NORMAL_GROUP_5) {
+			rxd += 6;
+			if ((u8 *)rxd - skb->data >= skb->len)
+				return -EINVAL;
+
+			rxv = rxd;
+			/* Monitor mode would use RCPI described in GROUP 5
+			 * instead.
+			 */
+			v1 = le32_to_cpu(rxv[0]);
+
+			rxd += 12;
+			if ((u8 *)rxd - skb->data >= skb->len)
+				return -EINVAL;
+		}
+
 		status->chains = mphy->antenna_mask;
 		status->chain_signal[0] = to_rssi(MT_PRXV_RCPI0, v1);
 		status->chain_signal[1] = to_rssi(MT_PRXV_RCPI1, v1);
@@ -410,17 +431,6 @@ mt7921_mac_fill_rx(struct mt7921_dev *dev, struct sk_buff *skb)
 			status->signal = max(status->signal,
 					     status->chain_signal[i]);
 		}
-
-		ret = mt76_connac2_mac_fill_rx_rate(&dev->mt76, status, sband,
-						    rxv, &mode);
-		if (ret < 0)
-			return ret;
-
-		if (rxd1 & MT_RXD1_NORMAL_GROUP_5) {
-			rxd += 18;
-			if ((u8 *)rxd - skb->data >= skb->len)
-				return -EINVAL;
-		}
 	}
 
 	amsdu_info = FIELD_GET(MT_RXD4_NORMAL_PAYLOAD_FORMAT, rxd4);