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From:   Johan Almbladh <johan.almbladh@anyfinetworks.com>
To:     nbd@nbd.name, lorenzo.bianconi83@gmail.com
Cc:     ryder.lee@mediatek.com, linux-wireless@vger.kernel.org,
        Johan Almbladh <johan.almbladh@anyfinetworks.com>
Subject: [PATCH] mt76: mt7915: fix injected MPDU transmission to not use HW A-MSDU
Date:   Fri,  4 Feb 2022 16:47:30 +0100
Message-Id: <20220204154730.166194-1-johan.almbladh@anyfinetworks.com>
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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>
---
 mt7915/mac.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mt7915/mac.c b/mt7915/mac.c
index 08ee78f6..1848fa16 100644
--- a/mt7915/mac.c
+++ b/mt7915/mac.c
@@ -1121,6 +1121,7 @@ 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) |
-- 
2.30.2