[PATCH wireless 1/4] wifi: mt76: mt7915: fix RCPI chain 3 mask in sta_poll RSSI extraction

[Joshua Klinesmith <joshuaklinesmith@gmail.com>]

The fourth receive chain RCPI uses GENMASK(31, 14), an 18-bit mask
spanning bits 14-31. It should be GENMASK(31, 24), an 8-bit mask
for the fourth byte, consistent with the other three chains and
with the RCPI3 definitions used elsewhere in the driver
(MT_PRXV_RCPI3 and MT_TXS7_F0_RCPI_3 both use GENMASK(31, 24)).

On devices with fewer than 4 antenna chains, the corrupted value
is masked out by antenna_mask in mt76_rx_signal(). On 4-chain
devices, this produces incorrect ACK signal strength readings.

Fixes: e57b7901469f ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Cc: stable@vger.kernel.org
Signed-off-by: Joshua Klinesmith <joshuaklinesmith@gmail.com>
---
 drivers/net/wireless/mediatek/mt76/mt7915/mac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
index 1c0d310146..946d2bd0d9 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
@@ -221,7 +221,7 @@ static void mt7915_mac_sta_poll(struct mt7915_dev *dev)
 		rssi[0] = to_rssi(GENMASK(7, 0), val);
 		rssi[1] = to_rssi(GENMASK(15, 8), val);
 		rssi[2] = to_rssi(GENMASK(23, 16), val);
-		rssi[3] = to_rssi(GENMASK(31, 14), val);
+		rssi[3] = to_rssi(GENMASK(31, 24), val);
 
 		msta->ack_signal =
 			mt76_rx_signal(msta->vif->phy->mt76->antenna_mask, rssi);
-- 
2.43.0