Re: [PATCH ath-current v3] wifi: ath12k: fix DMA direction for re-injected Rx buffers

[Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>]

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> On 10/23/2026 9:49 AM, Lorenzo Bianconi wrote:
> > Defragmented MPDUs that are re-injected into the REO are mapped with
> > DMA_TO_DEVICE, but all the Rx reap and teardown paths unmap them with
> > DMA_FROM_DEVICE. The DMA API requires the unmap direction to match the
> > map direction, so this violates the contract.
> > 
> > The mapping actually spans both directions, since the host has written
> > the buffer before the REO reads it and the buffer is read back by the
> > host afterwards, so DMA_BIDIRECTIONAL is the correct choice.
> > 
> > Add a common ath12k_dp_unmap_rx_buf() helper that selects
> > DMA_BIDIRECTIONAL for re-injected buffers, identified by the existing
> > ath12k_skb_rxcb::is_frag flag, and DMA_FROM_DEVICE otherwise, then use it
> > in all the Rx reap and cleanup paths. Map and unmap the re-injected buffer
> > with DMA_BIDIRECTIONAL consistently.
> > 
> > Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
> > 
> > Fixes: 33322e3ef074 ("wifi: ath12k: change DMA direction while mapping reinjected packets")
> > Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
> > ---
> > Changes in v3:
> > - Set ATH12K_SKB_RXCB()->paddr before err_unmap_dma condition in
> >   ath12k_wifi7_dp_rx_h_defrag_reo_reinject().
> > - Link to v2: https://lore.kernel.org/r/20261023-ath12k-fix-dma-mapping-for-reinject-packets-v2-1-9f436a26dd72@oss.qualcomm.com
> > 
> > Changes in v2:
> > - Rely on ath12k_skb_rxcb is_frag field and drop reinjected one.
> > - Link to v1: https://lore.kernel.org/r/20261017-ath12k-fix-dma-mapping-for-reinject-packets-v1-1-b94860e18ba4@oss.qualcomm.com
> > ---
> >  drivers/net/wireless/ath/ath12k/dp.c           |  6 ++---
> >  drivers/net/wireless/ath/ath12k/dp_mon.c       |  5 ++--
> >  drivers/net/wireless/ath/ath12k/dp_rx.c        |  3 +--
> >  drivers/net/wireless/ath/ath12k/dp_rx.h        | 11 ++++++++
> >  drivers/net/wireless/ath/ath12k/wifi7/dp_mon.c | 17 +++---------
> >  drivers/net/wireless/ath/ath12k/wifi7/dp_rx.c  | 37 ++++++++------------------
> >  6 files changed, 31 insertions(+), 48 deletions(-)
> This conflicts with recently added:
> febe1f8cbccc ("wifi: ath12k: avoid double DMA unmap of held monitor RX buffers")
> 
> Please rebase.

ack, I will fix it in v4. Thanks.

Regards,
Lorenzo

> 
> /jeff

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