[PATCH 7/9] mt76: mt7921: consider the invalid value for to_rssi

[sean.wang at mediatek.com]

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

It is possible the RCPI from the certain antenna is an invalid value,
especially packets are receiving while the system is frequently entering
deep sleep mode, so consider calculating RSSI with the reasonable upper
bound to avoid report the wrong value to the mac80211 layer.

Fixes: 163f4d22c118 ("mt76: mt7921: add MAC support")
Reviewed-by: Lorenzo Bianconi <lorenzo at kernel.org>
Signed-off-by: Sean Wang <sean.wang at mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/mt7921/mac.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
index 44b8918db95b..89a09381cfe4 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mac.c
@@ -461,16 +461,19 @@ int mt7921_mac_fill_rx(struct mt7921_dev *dev, struct sk_buff *skb)
 		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 = status->chain_signal[0];
-
-		for (i = 1; i < hweight8(mphy->antenna_mask); i++) {
-			if (!(status->chains & BIT(i)))
+		status->signal = -128;
+		for (i = 0; i < hweight8(mphy->antenna_mask); i++) {
+			if (!(status->chains & BIT(i)) ||
+			    status->chain_signal[i] >= 0)
 				continue;
 
 			status->signal = max(status->signal,
 					     status->chain_signal[i]);
 		}
 
+		if (status->signal == -128)
+			status->flag |= RX_FLAG_NO_SIGNAL_VAL;
+
 		stbc = FIELD_GET(MT_PRXV_STBC, v0);
 		gi = FIELD_GET(MT_PRXV_SGI, v0);
 		cck = false;
-- 
2.25.1