[PATCH] mt76: mt7921: fix antenna signal are way off in monitor mode

[sean.wang at mediatek.com]

From: Sean Wang <sean.wang at mediatek.com>

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. In 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: cbaa0a404f8d ("mt76: mt7921: fix up the monitor mode")
Reported-by: Adrian Granados <agranados at gmail.com>
Co-developed-by: Deren Wu <deren.wu at mediatek.com>
Signed-off-by: Deren Wu <deren.wu at mediatek.com>
Signed-off-by: Sean Wang <sean.wang at mediatek.com>
---
 .../net/wireless/mediatek/mt76/mt7921/mac.c   | 33 ++++++++++++-------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
index 47f0aa81ab02..8be422936b74 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
@@ -394,12 +394,34 @@ 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);
 		status->chain_signal[2] = to_rssi(MT_PRXV_RCPI2, v1);
 		status->chain_signal[3] = to_rssi(MT_PRXV_RCPI3, v1);
 		status->signal = -128;
+
 		for (i = 0; i < hweight8(mphy->antenna_mask); i++) {
 			if (!(status->chains & BIT(i)) ||
 			    status->chain_signal[i] >= 0)
@@ -408,17 +430,6 @@ 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);
-- 
2.25.1