[PATCH 5.16 075/285] mt76: mt7915: fix injected MPDU transmission to not use HW A-MSDU

Greg Kroah-Hartman
2022-04-12T07:46:01Z

From: Johan Almbladh <johan.almbladh@anyfinetworks.com>

[ Upstream commit 28225a6ef80ebf46c46e5fbd5b1ee231a0b2b5b7 ]

Before, the hardware would be allowed to transmit injected 802.11 MPDUs
as A-MSDU. This resulted in corrupted frames being transmitted. Now,
injected MPDUs are transmitted as-is, without A-MSDU.

The fix was verified with frame injection on MT7915 hardware, both with
and without the injected frame being encrypted.

If the hardware cannot do A-MSDU aggregation on MPDUs, this problem
would also be present in the TX path where mac80211 does the 802.11
encapsulation. However, I have not observed any such problem when
disabling IEEE80211_HW_SUPPORTS_TX_ENCAP_OFFLOAD to force that mode.
Therefore this fix is isolated to injected frames only.

The same A-MSDU logic is also present in the mt7921 driver, so it is
likely that this fix should be applied there too. I do not have access
to mt7921 hardware so I have not been able to test that.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mediatek/mt76/mt7915/mac.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
index a1da514ca256..d1a00cd47073 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
@@ -982,6 +982,7 @@ mt7915_mac_write_txwi_80211(struct mt7915_dev *dev, __le32 *txwi,
val = MT_TXD3_SN_VALID |
FIELD_PREP(MT_TXD3_SEQ, IEEE80211_SEQ_TO_SN(seqno));
txwi[3] |= cpu_to_le32(val);
+ txwi[7] &= ~cpu_to_le32(MT_TXD7_HW_AMSDU);
}

val = FIELD_PREP(MT_TXD7_TYPE, fc_type) |
--
2.35.1