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Felix Fietkau
36917c4e63
mt7996/mt7992 hand the firmware a HW MAC-TXP for AddBA req action frames
(MT_TXD7_MAC_TXD, set in mt7996_mac_write_txwi_80211()), but are otherwise
FW-TXP devices. On tx free mt76_connac_txp_skb_unmap() therefore decodes the
per-frame txp as a struct mt76_connac_fw_txp. For a MAC-TXP the fw_txp.nbuf
byte aliases the AddBA TID word (MT_TXP1_TID_ADDBA), which is always zero, so
the unmap loop runs zero times and the skb DMA mapping in buf[1] is never
unmapped. buf[1].skip_unmap is set unconditionally, so the generic DMA-ring
cleanup skips it as well.
Each AddBA req therefore leaks one TX DMA mapping, roughly one per
(re)association. With WED enabled these mappings are bounced through the WED
swiotlb pool, so under continuous client reconnect churn the pool is exhausted
after ~1-2 days, after which DMA mapping fails for WED, the WiFi MCU and other
on-SoC consumers.
Keep the deferred (token release) unmap that the design relies on, and add an
mt7996-specific txp unmap that inspects MT_TXD7_MAC_TXD and unmaps buf[1] from
the MAC-TXP layout for those frames, delegating to mt76_connac_txp_skb_unmap()
otherwise.
Fixes: cb6ebbdffef2 ("wifi: mt76: mt7996: support writing MAC TXD for AddBA Request")
Cc: [email protected]
Signed-off-by: Felix Fietkau <[email protected]>