[PATCH 2/2] wifi: mt76: mt76x02: report rx FCS errors to mac80211

[Devin Wittmayer]

When the fcsfail filter is enabled the hardware passes frames with a bad
FCS up to the driver, but mt76x02_mac_process_rx() never checks
MT_RXINFO_CRCERR and hands them to mac80211 without
RX_FLAG_FAILED_FCS_CRC. In monitor mode the radiotap flags byte then
never gets IEEE80211_RADIOTAP_F_BADFCS set and corrupted frames cannot be
told apart from clean ones.

Set RX_FLAG_FAILED_FCS_CRC from the descriptor CRC error bit, matching
mt7603, mt7615, mt7915, mt7921, mt7925 and mt7996.

Reported-by: 0072a70 <90307219+0072a70@xxxxxxxxxxxxxxxxxxxxxxxx>
Closes: https://github.com/morrownr/mt76/issues/38
Tested-by: 0072a70 <90307219+0072a70@xxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Devin Wittmayer <lucid_duck@xxxxxxxxxxxxx>
---
 drivers/net/wireless/mediatek/mt76/mt76x02_mac.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_mac.c b/drivers/net/wireless/mediatek/mt76/mt76x02_mac.c
index aa525adb6743..21f8b1e64101 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x02_mac.c
@@ -792,6 +792,9 @@ int mt76x02_mac_process_rx(struct mt76x02_dev *dev, struct sk_buff *skb,
 	if (rxinfo & MT_RXINFO_L2PAD)
 		pad_len += 2;
 
+	if (rxinfo & MT_RXINFO_CRCERR)
+		status->flag |= RX_FLAG_FAILED_FCS_CRC;
+
 	if (rxinfo & MT_RXINFO_DECRYPT) {
 		status->flag |= RX_FLAG_DECRYPTED;
 		status->flag |= RX_FLAG_MMIC_STRIPPED;
-- 
2.54.0